©2004-2022 F. Dörenberg, unless stated otherwise. All rights reserved worldwide. No part of this publication may be used without permission from the author.

Latest page updates: June 2022 (made into separate page; added ref. 230R8, 245B-245D)

Previous updates: January 2022 (inserted section on bombing); December 2021 (added ref. 230Q5, 230Q6, 230R13); 28 May 2021 (note: now about 800 literature references provided on the WW2 Rad Nav pages, almost all downloadable!); April 2020 (started complete overhaul & expansion of this page).

red-blue line


under construction

there was a number of other German beacon systems (ref. 1, 2A, 8, 26B, 230A-230C, pp. 7-19 in ref. 164B)


under construction

"Dezimeterwelle-Richtstrahl-Drehfunkfeuer" a.k.a. "Drehbake M" (UHF rotating-beam beacon). Ref. 2B, ref. 2C4, p. 122; ref. 2A, p. 87ff: DVL/Plendl, 261-268 MHz carrier frequency [≈1.1 m, so not truely "decimeter"], variable azimuth-segment dependent modulation (5.3-6.0 kHz in the 270°-0°-90° semi-circle direction, 8.0-10.0 kHz in the 90°-180°-270° semi-circle) , 100 W telefunken magnetron transmitter. Transportable, mobile (truck), and fixed-base installations. Antenne system: broadside planar array (4 m wide) of 18 ½λ-dipoles (2 stacked rows of 9?) + as many reflectors behind them, motorized rotation 1 rps (60 rpm!). 3 test sites: Rechlin, Schneeberg (≈ 90 km northeast of Nürnberg (Nuremberg), ≈ 30 km from the Czech border; with 1050 m the highest peak in the Bavarian Fichtelgebirge mountain range), the Wendelstein (1836 m, peak in the Bavarian alps, ≈ 60 km southeast of München/Munich, close to the Austrian border). Associated on-board receiver system: "Dezimeterwelle-Funkfeuer-Empfangsgerät AF2/3" a.k.a. "M-Gerät", comprising Telefunken BFO receiver "Lina", a Siemens "Zusatzgerät", a Siemens "Anzeige-Meßbrücke" with "Peilwertanzeige", and a "Rollkarte mit Lichtzeiger" (per DVL/Hepper) moving map/chart with light-pointer. Alternatively: standard AFN1 kick-meter ("Zuckanzeige") indicator, as for Lorenz ILS and Knickebein. Planned: course setpoint selection and auto-pilot coupling. Achieved RDF and course-tracking accuracy: +/1 1° and range up to 500 km. Development halted spring 1939 in favor of "Erika", due to complexity (temperature & auto volume/gain control), some issues with side-lobes of the radiation pattern, and reflections from terrain (e.g., cliffs & montains).


under construction

  • Elektra: long wave beam system (initially ca. 480 kHz, later 270-330 kHz), range over land 800-1200 km (500 and 300 kHz respectively), range over sea 1700-200 km (500 and 300 kHz respectively). Three antennas per beacon station. Transmitter power: 1.5 kW. Ref. 230A, 230B; 2C4, p. 121 etc.. Ref. 164B, p. 7: antenna height only 50 m and goniometer to swing the beam to the desired direction.
  • Stations (p. 6, 7 in ref. 164B): Huisen/The Netherlands (1940, 460 kHz, 10 λ spacing), Bayeux/France (Nov 1940, 300 kHz, 5.7 λ spacing, (temporarily?) dismantled late 1943); Stavanger (March 1941), Morlaix (?), one near Warsaw.
  • Elektra kurz (480 kHz, λ = 625 m; 1939-1941), Elektra lang (300 kHz, λ = 1000 m). Ref. 230K.
  • Dreh-Elektra? = Sonne?


under construction

  • Sonne ["Sun"]: long wave (several LF frequencies between 270 and 330 kHz vs 300 kHz nominal and 250-350 kHz), long-range system of the Kriegsmarine (navy). Lorenz. It was based on "Elektra", but rather than physically rotating a loop antenna, Sonne used three stationary antennas spaced about 1 km (about 3.86 wavelengths) and a single transmitter + goniometer, to electronically sweep the direction of the beams. Range over land 1200 km. Range over sea 2000 km. Transmitter power: 1.5 kW. Ref. 230A-230C, 230K1, 230K2, 230K3, 164B (p. 8, 9)). Collapsed hyperbolic system (extreme case of hyperbolic). Became operational June 1942.
  • Goldsonne. Ref. 164B, pp. 15-17: proposed by Dr Goldmann to overcome disadvantages of Sonne and Komet.
  • Goldwever/weber: a "Sonne" derivative that never became operational. Ref. 164B, p. 12: substitute for Komet. Ref. 38B.
  • Mond ["Moon"]: experimental system, intended to improve range and accuracy of "Sonne", while operating on higher frequencies (3 MHz, 6 MHz; 30-30 MHz per ref. 230A), at night. Ref. 2C4, p. 127.
  • Stern ["Star"]: an experimental Sonne derivative, operating at VHF frequencies, hence range basically limited to line of sight. Not developed to completion.
  • Esseker: Sonne derivative, with quicker indication of position.
  • Elektra-Sonne: beacon could be operated alternately as "Elektra" and "Sonne", to combine advantages of both. Range was intended to be increased by raising transmitter power to 60 kW. Three stations were built during 1944-1945 but were never operational. Ref. 230A. Bergen/Groet: ref. 278.

Consol sound

Sound clip of a Sonne/Consol sequence (42 sec)

(source: de.wikipedia.org, retrieved March 2020)

Consol sound

An other sound clip of a Sonne/Consol sequence (3 min)

(source: www.geocaching.com, retrieved March 2020)


under construction

  • Erich: "UKW-Phasendrehfunkfeuer"., i.e., a VHF rotating-phase navigation system.
  • Fernmeldetechnisches Entwicklungslaboratorium Dr. Ing. H. Kimmel ("Development lab for telecom equipment") in Munich, later Münchener Apparatebau für Elektronische Geräte Kimmel GmbH & Co. KG. Their 3-letter military manufacturer's code was "bes". Kimmel also made the "NF Phasenuhr" (audio frequency phase-indicator, with 360º scale) that was part of the on-board equipment of the 1943 Lorenz VHF rotating-phase navigation system "Erich" (very similar to the VOR system developed in parallel in the USA). Like "Bernhard/Bernhardine", the "Erich" system also used the EBl 3 radio receiver.
  • Ref. 2A; 2C4, p. 128 . R&D at Lorenz started in 1943, on the familiar/standard 30-33.3 MHz freq, based on a 1940 patent (nr ???). Antenna system: 4 vertical dipoles at 4 corners of a square with 1/8 λ sides, plus a central radiator (vertical dipole?). The 4 dipoles were excited with a (standard) 500 W landing beam beacon transmitter, unmodulated carrier only, via motorized rotating radio goniometer [antennas stationary!]. Creates a cardoid, rotating at 50 rpm, resulting in a 50 Hz amplitude variation at the receiver, similar to 50 Hz AM modulation. Central (omni-directional ) antenna powered by a separate 10 W FM-transmitter with constant 50 Hz modulation, referenced to "North" passage of the rotating cardioid. Phase difference between the two received 50 Hz signals [after AM and FM demodulation, respectively] is [linearly] dependent on the bearing from the beacon to the receiver. The [demodulated signals where compared] with an "NF-Phasenmesser" / "NF-Phasenuhr" ["AF phase clock"] with two electric motors driving an indicator pointer w.r.t. a 360° scale, via a differential gear. See blockdiagram in ref. This system is very similar to the simultaneously and independently VHF Omni-directional Range (VOR) beacon [here too: "Range" is not "distance" but "directional beacon"]. For the given cardioid radiation pattern, the achievable accuracy was "only" 1°, and the fact that demodulators and cockpit indicator were needed,[and the industrial stage of the war], the project was cancelled in favor of the "Hermes/Hermine" "talking beacon", [with a slowly rotating "4 vertical dipoles + central omni antenna" antenna system] which only required the existing standard receiver.


under construction

An interesting beacon system is the Hermes "Sprechdrehbake" system ("rotating talking beacon"). Also referred to as Hermine, which was also the name of the airborne equipment set. The system was originally developed in response to a tactical requirement formulated during the second part of 1942, as a navigational aid for the purpose of giving an approximate bearing to single-engine night fighters engaged in "Wilde Sau" [lit. "Wild Boar"] air-defence operations. The pilot could determine the bearing from the beacon, without having to look at an instrument. The beacon stations (FuSAn 726) transmitted real-time voice-announcements of the beam azimuth, every 10º. I.e., the numbers 1 - 35 (multiples of 10º, as standard on compass scales), and the "station call-sign" at 360º = 0º = True North passage. Each digit was pronounced separately: e.g., "12" = "1-2" (as is proper /standard practice in worldwide aviation radio comunication to ensure intelligiblity, except in France), not "twelve". The voice stream was pre-recorded as an optical track on an endless/continous film strip ("Tonfilm") + photoelectric cell; rotated with the shaft of the antenna system (--> "optical disk"?). The voice signal was transmitted (FM modulated) with an omni-directional antenna. At the same time, and on the same frequency, a strong constant audible 1150 Hz tone was transmitted. However, it was transmitted with a rotating cardioid antenna pattern. The null of this pattern ( = no 1150 Hz interference signal) coincided with the direction as announced by the voice announcement at that very moment. So, the voice could only be heard (briefly) in that particular momentary direction. Due to the width of the null (effectively about 15° (ref. 8), equivalent to (360°/15°)x60=2.5 sec), the immediately preceding and following announcement was only partially audible, at much reduced volume.

The airborne counterpart, FuG125 "Hermine-Bord", comprised (eg per ref 2A2) the standard EBl 3 receiver, its FBG2 remote control panel, and a small audio-amplifier (model V3a or ZV3), (separate?) FM demodulator (TBC), Anzeigezusatz ZuG 125, and nav instrument AFN 2. Antenna shared with VHF R/T radio TRX FuG 16 ZY.


  • The system was developed in 1943/44 by Ernst Kramar et al of the Lorenz company. Range: Range 200-250 km at 15000 ft  (vs 250 km range marked in maps/charts of ref. 210x).
  • Ref. 185H: Yet another receiver was developed by the Lorenz Company (Dr. Kramar) which was designated FuG 125, code named “Hermine.” The receiver was made up of the EBl 3 F receiver, the FBG 2 remote control, a V3a amplifier for volume control. A FuG 16 ZY antenna was connected in parallel. This unit was designed for IFR weather. On the 14th of September 1944 an order of 18,000 units (!) was given to the Stassfurter-Rundfunk-GmbH [Staßfurter Rundfunk-Gesellschaft mbH, the 1932 radio production subsidiary of Staßfurter Licht- und Kraftwerke AG]. In the latter part of the war, only a few dozen units were actually delivered, and used in the Me 109, Fw 190, Ta 152, Do 335 and 15 Me 262
  • Ref. 249A: FuG125 "All fighter airplanes (other than Me 163) to be equipped with FuG 125 ( = EBL.3 + ZV 3, ZV3a) for "Hermine" reception; planned intro of potentially obsolete FuG 15Y (first in Ta 152 aircraft), continued equipage with FuG 16 ZY. Combat aircraft: FuG 125 not to be installed in Ju 88, Ju 388. Do 355, Me 262; Ar 234 to get at least FuG 125 racks. He 177: K3 and FuG 17Z to be considered. Ju 287: needs antenna"
  • Ref. 6G §58-64: The Hermine [-->Hermes ground station] system was originally developed, in response to a tactical requirement formulated during the second part of 1942, as a navigational aid for the purpose of giving an approximate bearing to single-engine night fighters engaged on “Wilde Sau” operations. By the time the initial difficulties in development had been overcome Wilde Sau night fighting had almost ceased; it was found however that Hermine could be used to advantage by day fighters, and it came into operational use. 60. An accuracy of ±5° was assumed, but it was found in practice that this could be improved upon to ±3° by experienced pilots. Thirteen or fourteen ground stations were in operation by Easter 1945 which, P/W claimed, gave complete coverage of the Reich. It was intended to fit two Schlechtwetter (bad weather) Fighter Geschwader with the necessary airborne equipment, and this program had been one-third completed by May 1945. One P/W had heard that ten to fifteen Me.262's of K.G.51 were amongst the aircraft so equipped. The following may be added in modification of the description of the Hermine system given in A.D.I.(K) 125/1945 [ = ref. 6C] , paras.59 to 62. The Hermine rotating beacon transmits a continuous tone on which is superimposed a speaking clock which counts from 1 to 35, each figure representing tens of degree. Over an angle of about 15° the continuous tone falls to a minimum and rises again. During this period the voice appears to become more audible and the pilot can estimate where the minimum of continuous tone occurs, and so obtain his bearing from the beacon. The beacon recognition is given by means of a self-evident code name for example, "Berolina” for Berlin – which is spoken by the voice in place of 000°.
  • Ref. 6G §58-64: The airborne equipment is the FuGe 125 consisting of the E.B.L.3 with the Tzg (Telephoniezusatzgerät) which enables the 30.0 - 33.3 mc/s transmission picked up on the E.B.L.3 receiver to be heard in the pilot's headphones. Though the Hermine beacons were fully operational, there was a scarcity of FuGe 125 sets, as a result of which practical experience of this system was too limited to judge of its efficiency or to lead to further improved tactical requirements been formulated.
  • Ref. 2A2 p. 89/90; 2C4, p. 128: 120 W transmitter output power; 1150 Hz Störton; Range 200-250 km at 5km/15000 ft altitude. Accuracy 3-5°. Antenna system: 4 vertical dipoles with "Drehfeldspeisung" at 4 corners of a square with 1/8 λ sides, plus a central radiator (vertical dipole?). Antenna system rotating at 1 rpm. Purpose: enable fighters to home to airfield. Five beacons operational in January of 1944, 13-14 by Easter of 1945, spread out over the Reichsgebiet ( = area of the German Reich , typ. understood to mean the end of 1937 borders of "Germany proper", excl. occupied territories). Receiver: Lorenz FuG 125 "Hermine" = E Bl 3 F [F = Fernbedienung = remote control] + Zwischenverstärker ZF 3 amplier + Anzeige-Zusatz[gerät] or Zuckanzeigegerät ZuG 125 + one AFN2 [see Fig + text above, add #]. Airborne receiver shared antenna with the VHF R/T transceiver FuG 16 ZY. But: controary to the ground stations, aircraft equipment sets did not become available until close to the end of the war, so only a small number of Me 109, FW 190, Ta 152, und Me 262 of some Bad weather groups were ever equipped, incl. 15 Me 262 of Kampfgruppe K.G. 51.
  • Ref. 164B (pp. 13-15): antenna system atop a 16 m tall steel tower, accuracy ~2°, headphone in a/c, transmitter 150 W type AS3 (Lorenz landing beacon TX), 30-33.3 MHz (HF/VHF); antenna system had gain of single dipole; configuration: 2 pairs of vertical dipoles at 4 corners + 1 central omni for voice announce; antenna current ratio dipole pair-1 : pair-2: omni = 1.0 : 1.8 : adjusted to min (?); bandwidth +/- 0.5 MHz without changing length of the 4 outer dipoles  (30-33.3. MHz when changing length); antenna system mechanically rotated at 1 rpm; feedlines through hollow shaft --> implies contact slip rings, or capacitive no-contact such as for Bernhard; noise transmission turned of during station ID announcement (1100 Hz, not 1150?); single/same transmitter for tone and voice? ; monitoring w aircraft type RX at 200-300 m, with audio via telephone cable to control/equipment room. Hermine/FuG125 had to be minor modded to increase audio bandwidth (with add'l on/off ctl).
  • Ref. 229Q, p. 92: cardioid pattern.
  • Fifteen known He-stations. Ref. 2A2: by January 1941 five groundstations were operational, 13-14 by Easter of 1945, spread out across the entire Reichsgebiet.
  • ?? vs 5 on 1-1-1945 per ref 292 (Germany only?) - TBC
  • Add standard map with locations.


Fig. XX: Table with the location of all Hermes stations

(source: ref. 210A, 210B, 210F, and ref. 230S3 which is a kmz file that can be viewed in Google Earth)


Fig. XX: Early 1945, five Hermine stations were operational

(source: adapted from p.1 of ref. 292)


Fig. 51: Principle of the "Hermes/Hermine" talking beacon system

(source photo: deutschesatlantikwallarchiv.de)


Fig. 53: Radiation pattern of the rotating "null" beam

Hermes sound - audio file still to be created...

Simulated sound of a "Hermes" beacon (60 sec rotation)

(source: ? © ? used with permission)

In these UHF installations, the transmitters did not rotate with the antenna system: they were located in the small stationary building below the antenna system. This arrangement requires a rotary coupler between the antenna system and the transmitters. This may have been implemented as a set of slip-rings on the shaft of the rotating antenna system. Note that a slip-ring approach ("HF-Schleifringkopplung") was actually used in several German systems, for instance the FuMG 404 "Jagdschloß" radar (designed by GEMA, built by Siemens). Ref. 151. The largest version had a 24 m wide antenna array system (4 x 16 horizontal dipoles) that weighed 25-30 metric tons. It rotated at 10 rpm, with the central shaft driven by a 75 kW 3-phase motor. It was a UHF system (120-240 MHz, depending on the version). It transmitted 1- 2 μsec pulses of 8-20 kW, with a pulse repetition frequency (PRF) of 500 / 3000 Hz.

However, there is also a 1936 Telefunken patent (nr. 767525), by Adalbert Lohmann. He was Telefunken's expert on rotary navigation beacons, including the Bernhard system. This patent is explicitly for the directional antenna system of the Telefunken rotating beacon station. It proposes a method for a contact-free rotary coupler: no contact resistance, no arcing at brushes! The coupler comprises two sets of stator and rotor disks that form capacitors. See Figure 16. The disks are installed coaxially: the rotor plates are fixed to a rigid shaft (preferably ceramic), and the stator plates to the housing of the coupler. The transmitters are wired to the edge of the respective stator plate. Note that in the VHF (30 MHz) Bernhard system, the transmitters are located on the same rotating platform as the antenna system. Hence, no rotary couplers were required for between the transmitters and the antennas. Of course, in this configuration, electrical power for the transmitters must be provided via slip-rings.

Bernhard antenna system

Fig. 16: Contact-free rotary coupler for RF signals

(source: the 1936 Telefunken/Lohmann patent 767525)


under construction

  • Komet (FuSAn 712) ground station + Komet-Bord (FuG 124) equipment set in aircraft; system (with acccuracy +/- 1.5° ?). Long-range (up to 3000 km)
  • Ref. 2A2. Ref. 2C1. Ref. 2C2. Ref. 2C4, p. 123. Ref. 2C5. Ref. 6D. Ref. 6G (ADIK 357/1945). Ref. 20. Ref. 93. Ref. 101. Ref. 141. Ref. 184F1. Ref. 185H. Ref. 230B. Ref. 230P2. Ref. 230S1, 230S2. Ref. 235L. Ref. 241. Ref. 284.
  • TBC: precursor to Komet was Schweres Funkfeuer "Dora" (ref. 6G); longwave (211 kHz); @ Kölby, als @ near Erfurt?, Do-2 @Morlaix/France (ref. 230P2, not finished)
  • Motivation/need/result:
  • ref. 6G (ADIK357/1945): "in 1942 the question of navigation over the Atlantic stood in the limelight. As the He 177 was supposed to be coming into service shortly to enable K.G.40 to reach further West, the need for navigational equipment of longer range became acute."
  • 1942: "Battle of the Atlantic" (Allied naval blockade of Germany since start of war; Kriegsmarine U-boats/warships (also some Italian navy)+ Luftwaffe attacking US-to-UK Allied convoys) still going strong vs Allied gainung upper hand by end of 42. German plans to attack USA with long range bombers?
  • Ref. 230S2:out of Kölby telegram 1944: secret telegram from the Gen. Nachrichtenführer (Director General of the Signal Corps) to Luftnachrichten Inspektion 5 Abt. III; instructions to halt construction and dismantle installations per instructions Nr. 35513/44 (secret) of same date, staff & guards to be redeployed , Komet at Kölby to remain at disposal of industry for further test/eval, no dismantlement yet of Komet stations pending special instructions upon test results; dated 27 July 1944. (Interesting sidenote: telegram was written in "Robinson 2", i.e., the Führungszug des Chefs des Generalstabes der Luftwaffe [Chief of the Luftwaffe General Staff].
  • Proved impossible/impractical to properly adjust/calibrate. Development and evaluation was done from 1941 through the end of the war (vs. abandoned per ref. 6D).
  • Then: Why mention/describe? interesting from technical point of view, step in radnav
  • Antenna system, rotating beam concept, radiation pattern
  • Ref. 284: "said to work on a principle similar to that of the Sonne".
  • Ref. 164A, pp. 51-56: at Ismaning, 2 forms, antenna configs  -general vs at Ismaning, concept, time intervals / sequence, recorder, performance
  • Ref. 184F: "Kleinbasissystem" vs "Großbasis" : antenna system basis length vs wavelength; geart-circle propagation path, same terminolgy for RDF and beam system. Experiments with bais up to 12 WL, conclusion: 2 WL optimal wrt error elimination. switching the diagram (Umtastung) instead of Minimum RDF system. 3-Strahlersystem: Central antenna + Aussenantennen at 1 Wl from central, on one line. Umtastung @ 70 Hz, guide beam rotation with 5 sec period ( = back & forth?). !!!! System usable within a limited angular range to left and right of the Mittelsenkrechten = direction perpendicular to the base line if the antenna system. To identify the ref direction of a particular beacon, an ident is transmitted when beam sweeps through range of -1.5° to + 1.5° of the prime direction. 70Hz pattern switching results in 70 Hz tone at output of the receiver, amplitude is plotted. During passage of ID range, no 70 hz is received --> omni ID transmission with central antenna only, instead of rapidly switching pattern. --> brief sharp dip in signal plot (vs brief peak in plot?)Printer prints across the slowly moving paper tape, lines bottom to top, porinted line starts at bottom upto RX amplitude, printer synchronized to beam rotation!  = start-stop Hellscheiber printer! relatively simple. similar to amplitude plotting track of HS120/Psch120 !!!!!
  • Antenna system comprised concentric ring-segments of vertical antennas for multiple operational HF frequencies (short wave; 3-25 MHz); angular spacing of 3° --> 120 antennas per full ring, used pair-wise (diametrically opposed) at a time, in combination with omni-directional antenna at center of the rings. Development / evaluation / experimental 1941- EOW.
  • Antenna system not full circle --> beam sweeping back & forth over arc segment?
  • Limited arc segments, not full circles: reason???  due to experimental or need-based over Atlantic and or Russia or 360° beam rotation possible, since central anetnna + switching antenne pairs - but then, why need even arc segments instead of just single antenna pair + central antenna?
  • Central transmission direction = axis of symmetry between the 2 antenna arrays - not the along the axis of the central antenna to antenna #11 in each arc segment. What was the angular sweep of the beam?
  • two opposite groups of 4 adjacent vertical antennas active at any given time, phase differences between them per ref 230S1.
  • Smooth sweep or stepwise-rotating (suggested based on groups of 4 adjacent antennas being switched)?
  • Beam width vs accuracy measured at Gaeta and Palermo (ref 184F4)?
  • ref. 6G (ADIK357/1945):"Oscillating" with 100 sweep passages / min = 1.2 sec/cycle. Operating freq: 5, 9 or 12 MHz = 60, 33, 25 m WL for use with FuG10. 19 control huts!
  • Large HF ground station with an antenna array with 127 (120?) masts and 19 control huts (boxes?), with "Kometschreiber" bearing recorder/indicator in the aircraft (FuG124).
  • Rapidly alternating overlapping beams/rad papterns, but not "complementary keyed" like Kn. Alternating used to reduce/eleminate certain errors ue toradio propagation effects at RX. Also marker signal when passing reference direction, as with TFK Kompass stepwise rotating beacon and derived systems.
  • !!!!!!! ref. RL 3/378: "Komet is a shortwave radio beacon with rotating guide beam. To eliminate the effect of elevation angle of the skywave, the guide beam is only used within about 1.5° of the perpendicular of an antenna basis [central vertical antenna + pair of outer vertical antennas on straight line], and a multitude of antenna basses is required to cover a larger pointing direction range".
  • Transmitter:
  • 3 kW. Refs? Mfr? Type?
  • Ref. 284 claims "Normally only on one frequency, but all could be used simultaneously" - unlikely, since seems would require 3 separate transmitters, as TX of that era just not frequency agile.
  • Station positions from Luftwaffe/Luftnachrichten map extracts + list etc:
  • Ref. 8. Experimental stage only (Bordeaux/France, Kølby/Denmark vs. Wullenweber HFDF at Kølby, ref. 230S1).
  • Ref. 20: Komet Experimental installation with single antenna pair at Ahlimbsmühle/Germany (ca 50 km north of downtown Berlin). A complete system was also installed 1944 in the Ismaninger Moos bog area (ca. 15 km northeast of downtown Munich), but never operational. Circle diameter 2λ. Primary frequencies 5470 kHz (λ ≈ 55 m), 8345 (λ ≈ 36 m), 11455 kHz (λ ≈ 26 m).
  • Ref. 210A (map Reichsgebiet; Stand 15 June 1944): Ko-1 @ Kölby, dashed icon + 15.9.44 = planned/under construction, est'd completion 15 Sept 1944; Ko @ München [Munich; actually Ismaninger Moos, 25 km east of down-town Munich], solid icon --> built to completion.
  • Ref. 201C (Westfront):
  • Ref. 210D (map Ostraum; Stand 15 June 1944): Ko-1 @ Kölby/Kølby (in the far north of Denmark, ca 14 km west of Nibe, ca 30 km west of Aalborg, just [ca. 500 m] southwest of the village of Kølby), solid box icon, but date 15.9.44...; Ko-4 @ Bucharest, - icon gestrichelt + "unbestimmt"--> "planned or under construction", est'd completion date "undetermined".
  • Ref. 210E (map Westraum, Stand 15 June 1944): Ko-1 @ Kölby, dashed icon + 15.9.44 = planned/under construction, est'd completion 15 Sept 1944; Ko-2 @ Bordeaux (@ NE ?), dashed icon + "unbestimmt" = planned/under construction, est'd completion date "undetermined"; Ko-3 @ Labouheyre, ca 75 km SSW of down-town Bordeaux); Ko-2 & Ko-3 - icon gestrichelt --> "planned or under construction", expected date of completion 15 Oct 1944.
  • Ref. 210F (map Funknavigationsanlagen; Stand 1-Oct-1944): Ko-1, planned or under construction, and the Ko (no #) north of Munich/Germany.
  • Ko-1 @ Kölby/Kølby, Ko-2 @ Bordeaux, Ko-3 @ Labouheyre, Ko-4 @ Bucharest, Ko @ München [Munich; actually Ismaninger Moos, 25 km east of down-town Munich, half way MUN and MUC Airport], Ko @ Ahlimbsmühle/Schorfheide [70 km N of Berlin]
  • !!!! ref 230P2 (June 1944): Ko-2 "Laharie", Ko-3 "Labouheyre, neither one finished/operational.
  • Possibly 1.5 km NE of Laharie (400 m east of the E70 freeway/motorway/highway, a community km east of village of Onesse-Laharie (Onesse-et-Laharie until 2013), in the "Les Landes dept. (dept. 40), 20 SSW of Ko-2/Labouheyre, 95 km southwest of down-town Bordeaux. There was a German Adcock RDF site there.
  • Ref. 184F: Ahlimbsmühle: 5740 kHz (52 m WL), 8345 kHz (36 m WL), 11455 kHz (26 m WL), 1942-1943.
  • Ref. Trenkle FN FFV bis 45: Ahlimbsmühle military site, construction started in 1939, test site for shortwave rotating beam beacon "Elektra Kurz" until 1941;
  • Expand ref. 20 (pp. 64 ff).
  • Ref. RL 3/378: 1 November 1944: +/- 1° accuracy improved from 74% to 98% between January 1944 and June 1944. At Ko-1: unacceptable amplitude and phase distortion due to undesirable coupling between 180 antennas [FD: which should not have been a surprise]. Proposal from Ferd. Braun Institute to sequentially measure antenna bases that are spaced by 30°, and combine measurents to obtain azimuth. Measurements in east-west azimuth abandoned due to the "military situation". Problems obtaining the required goniometers from industry, and

wikipedia: FuG 124 Komet: In 1942 with the He 177 and the "Battle of the Atlantic" in full swing the Germans started the development of a long range beacon system called Komet. This was based on pre-war work done by Lorenz. Its consisted or a rapidly rotating beam (electronic not mechanical) transmitting at 3Kw and at frequencies between 5 and 12 MHz. The signals were picked up using a FuG10K receiver and processed by the FuG 124 Komet processor which printed the results out on a paper strip.(The Kometscriber). Two test stations were built in 1944.[5] There were several problems which resulted in it never being used. The antenna array was vast using 127 aerials and 19 control huts. It was discovered that it would be easy to jam and as it was now 1944 with German forces falling back on all fronts there was no longer a requirement for it. The few Fug124 receivers built were only used on the ground for R&D work.[6]

ref. 6D: A.D.I. (K) Report No. 357/1945; §37-43 "Komet": In 1942 the question of navigation over the Atlantic stood in the limelight. As the He 177 was supposed to be coming into service shortly to enable K.G.40 to reach further West, the need for navigational equipment of longer range became acute. A year or so earlier Professor von HANDEL had categorically stated in a lecture that a long-range navigational system based on pulse would inevitably be extremely inaccurate. In view of Professor von HANDEL's views on pulse systems, an improved form of Sonne which would give much greater ranges and be less susceptible to night effect was given high priority. The system evolved was called "Komet" and experimental stations were erected at Bordeaux and Kolby (see A.D.I.(K) 364/1944). The ground station called for an array of no less than 127 masts and 19 control huts in order to cover a 90° sector. It worked admirably provided a 10° sector only was covered, but as soon as the planned 90° sector was put into operation, mutual interference between the masts arose and the various lobes radiated were no longer of symmetrical pattern, with the result that large errors crept in.Research on this delayed the project considerably. After the invasion when long distance reconnaissance in the Atlantic was no longer practical politics, the Komet system was given up without ever having been effectively used. The development people were the more pleased to dispense with it since it left the German radio research and industry free to deal with other more urgent matters. The beacon was to operate on frequencies of 5000, 9000 or 12,000 kc/s received on the FuGe 10K, and it was estimated that ranges up to 3000 km would be obtained. The system employed was to be similar to that used in the Sonne but instead of obtaining one reading per minute, oscillation of the beam was to be speeded up to give 100 readings par minute. The true bearing of the aircraft was automatically recorded by the FuGe 124 which was known as the Kometschreiber. The recording took the form of a series of vertical lines, one for each reading, printed on a strip of paper. At the same time as the lines were printed the Kometschreiber recorded the section of the swept area in which the aircraft was flying, thus giving what amounted to a rough position. The fine reading was obtained from the length of the recorded lines. Any inaccuracies due to night effect could be easily eliminated by averaging the length of the lines, as recorded, on the paper strip, by eye.


Fig. XX: TABLE - Detailed location of the Ko-stations and their primary parameters

(Sources: ref. 210A-210F AND OTHERS)


Fig. XX: Location of the Ko-stations and the great-circle arcs of their central transmission direction

(based on angles stated in ref. 230S1, 210A-210F; listening stations at Gaeta, Palermo,Termini (all in Italy) also marked (at 1800 and 2100 km from Ko-1))


Fig. XX: Ko-stations marked on various 1944 maps of the Luftwaffe Signal Corps (Luftnachrichten)

(source: adapted from ref. 210A-210F; the experimental Ko station at Ahlimbsmühle (north of Berlin) does not appear on these maps)


  • FuG124 "Komet-Bord"
  • "Kometschreiber" + Zusatz?
  • ref. 6G (ADIK357/1945): FuGe 124 which was known as the Kometschreiber. The recording took the form of a series of vertical lines, one for each reading, printed on a strip of paper. At the same time as the lines were printed the Kometschreiber recorded the section of the swept area in which the aircraft was flying, thus giving what amounted to a rough position.

FuG 124 "Komet-Bord" only/incl. "Kometschreiber" Schreibzusatz. Received signal amplitude printed out on a wide/tall paper strip. Like standard strip chart recorder. Printing meachism unclear.

Used in combination with which (standard) shortwave radio receiver? (E10K=EK of the FuG10K set only covered 3-6 MHz, vs Komet 5-12 MHz, E10K1/EK-1: 5.3-10 MHz, 1941; E10K2=EK2 RX of the FuG10K-2 set with 6-12 MHz, or E10K-3 = EK3 (1943) of the FuG10K3 set with extended freq range of 6-18 MHz. None of the EK covered all three frequencies...). Ref. 284: p. 12:  "FuG 10 aircraft receivers E10K and E10K2 between 3 and 18 MHz.


Ref 184F: Printer prints across the slowly moving paper tape, lines bottom to top, porinted line starts at bottom upto RX amplitude, printer synchronized to beam rotation! = start-stop Hellscheiber printer? relatively simple. similar to amplitude plotting track of HS120/Psch120 !!!!! ADD FIG FROM HS120 PAGE


Fig. XX: Experimental "Kometschreiber" printer / strip-chart plotter

(source: Trenkle FN & FFV bis 45 p. 91)

From ref 184F5. ".....vom Komet her vorhandene Schreiber nach dem Hell-Prinzip, eingefärbte Schreibspirale + Schneide + Schreibmagnet; Drückt die Schniede kurz auf die Spirale, so entsteht auf dem Papier ein Punkt, dessen lage von der augenblicklichen Stellung der Spirale abhängt. Spirale läuft mit der Gruppenfrequenz des Senders umlaufzeit 5 sec (aus mechanischen Gründen !?), Schneide darf nur 1x pro Umdrehung = 5 sec anziehen. Von den vorhandenen 50 Senderimpulsen pro Sekunde nur alle 5 Sec einen wirksam werden zu lassen. Auswahl geschieht mittes einer 2. Impulsfolge, sog. Suchimpulse....  Doppelsprirale, halbe Spindeldrehzahl, zwei [identische] Schriebe in verkleinerten Massstab übereinanderwie beim Siemens-Hell-Schreiber...." --> not start-stop?

Hellschreiber (as may be clear from the header across the top this page - this page is part of my Hellschreiber website). I refer to my "Hellschreiber - how it works" page.


Fig. XX: Concept of the Hellschreiber printer for recording of radio pulses received from ionospheric radio propagation tests

(source: adapted from ref. 184F5)

INSERT FIG 9 etc from ref 184F


Fig. XX: Print-out from the experimental "Kometschreiber" at a monitoring ground station

(source: adapted from ref. 184F4)




Fig. XX: Aerial photo of the remnants of the antenna foundations of the "Komet" installation at Kølby

(source: collection M. Svejgaard, used with permission March 2020; note: current (2022) satellite images of the same area no longer show the remnants.)


Fig. XX: Antennas of the "Komet" at Kølby - side view of one radial line of antennas

(source: adapted from 1945 site survey in ref. 230S1)


Fig. XX: Antennas of the "Komet" installation at Kølby - top view of one half of the antenna array

(source: adapted from 1945 site survey in ref. 230S1)


Fig. XX: The "Komet" installation at Kølby (outer ring antennas were never installed, foundation only)

(presumably May-June 1945, photo taken by 1st Lt. F.G. Tillisch; source: collection M. Svejgaard, used with permission March 2020)


Fig. XX: The "Komet" installation at Kølby - one half of the antenna systems

(presumably May-June 1945; source: collection M. Svejgaard, used with permission March 2020)


Fig. XX: The "Komet" installation at Kølby - close-up of the base of the antennas and chicken wire ground screen

(presumably May-June 1945; source: collection M. Svejgaard, used with permission March 2020)


Fig. XX: The "Komet" installation at Kølby - daisy-chained interconnection of the groups of four adjacent vertical antennas

(source: adapted from ref. 230S1)


Fig. XX: A pile of antennas of the Komet at Kølby - abandoned at nearby Aalborg Air Base

(ca. 2004; source: © M. Svejgaard, used with permission March 2020)


On a German Signal Corps map of 15 June 1944 (ref. 210E), the Ko-2 map icon is dashed (see Fig. xx above), meaning it was "planned or under construction". The expected date of completion is marked next to the icon as "undertermined". Howver, per ref. 230P2 (30 June 1944), Ko-2 at Laharie (like Ko-3 at Labouheyre) was not to be dismantled, due to operational and test needs. This implies that, at that time, Ko-2 must have been constructed and at least partially operational. However, available Allied and post-war French aerial photos do not show any signs of a Komet antenna installation in that area.

Modern time aerial photos do not show remnants of German WW2 antenna installations. The 1945 black & white insert in the next Figure does show remnants of a Luftwaffe/Luftnachrichten radio direction-finding Adcock installation (a square with a vertical antenna mast at each corner, each with three guy-wire anchor blocks) and of the German prison camp Frontstammlager (Frontstalag) 195. This camp was used exclusively for “French soldiers of indigenous origin”, i.e., subjects from French colonies in Africa. Until December of 1940, this camp was located at Saint-Omer on the Channel coast, where it was opened in August of 1940. The camp at Laharie was closed in 1943. Apparently, it held as much as 3000 prisoners, at some point including four British PoW’s.


Fig. XX: Recent satellite image with black & white insert from a 1945 RAF sortie that shows concrete foundations of an Adcock antenna

(source color aerial image: remonterletemps.ign.fr, retrieved June 2022)

About 4 km northeast of Laharie, there was another installation of four antennas. Unlike the Adcock installation with its standard square footprint, this installation had a rhombic footprint. It measured 185x90 m (≈ 600x295 ft). At each corner, there were four concrete foundations. This is typical for a vertical antenna (or antenna mast) with three anchors.


Fig. XX: Recent satellite image with black & white insert from January 1945 that shows concrete foundations of 4 antennas

(source color aerial image: remonterletemps.ign.fr; 1945 insert: remonterletemps.ign.fr; retrieved June 2022)




Fig. XX: Aerial photo of the Komet site at Labouheyre - period 1950-1965

(source: remonterletemps.ign.fr, also at geoportail.gouv.fr; retrieved June 2022)

Per recent (2018) aerial photos with 20 cm (8 inch) resolution (see here), there are no remains visible at the site.




Fig. XX: Komet Ko-4 marked on a 15 June 1944 map of the Luftwaffe Signal Corps (Luftnachrichten)

(source: ref. 210D; the handwritten note states that the completion date is "unbestimmt" = undetermined; Ko-4 was collocated with Sonne-9)

I have no information about this station. If you have any info, please contact me.



Also referenced as Erding (eg ref. RL 3/378). Ref. RL 3/378 1 June 1944: continuous measurements done at Erding, in support of "Weiterarbeit" of teh Lorenz company at the front-line stations in Denmark [Ko-1] and in the south of France [Ko-2, Ko-3].


Experimental, long term radio propagation tests, proof-of-concept --> does not require complete Komet antennas system.

ref. RL 3/378: .  ref also mentions Landsberg as reception station.

Located 61 km north of the city center of Berlin.


Fig. XX: Recent aerial photo with black & white insert from 9 May 1944 RAF sortie shows concrete antenna mast foundations

(source aerial background photo: bing map; the features (concrete blocks) inside the orange oval are still visible today)


Fig. XX: Funkstation (F.St) with the same antennas marked on a 1952 update of a 1934 ordnance survey map (Meßtischblatt)

(source original 1934 Meßtischblatt 2947 "Gollin": deutschefotothek.de, source of post-war marked up map: Brigham Young University library via Mapster; "F.St." is either "Funkstelle" (transmitter station) or "Forschungsstelle" (research station); the area with "W.T." ("Wasserturm" = water tower) is a corner of Hermann Göring's personal Feldflugplatz airstrip for visits in his Ju-52 to his nearby Carinhall countryside estate, demolished 20 April 1945 by German troops, on Göring's orders)


under construction

Post WW2 systems (german and other): Navaglobe (1946), Navar, Navascope, Ray-Dist, VORTAC, VOR-DME, Navarho/Navarho-H/-HH/-Rho, Radio Mesh System, MLS, SatNav, etc. : outside scope.

Other, non rotable/rotating - out of scope / cover elsewhere

  • Schwanboje: ref. 6D, §22-2 [ = waterborne V.H.F. beacon dropped by parachute and originally used by K.G.40 for marking convoys or submarines = locating beacon]
  • Diskus: ref. 6D, §75.
  • Wullenwever: p. 12 in ref. 164B. (RDF?)


Below is a listing of patents related to radio direction finding, radio location, radio navigation (generally covering the early 1900s through WW2).Patent source: DEPATISnet. Patent office abbreviations: KP = Kaiserliches Patentamt (German Imperial Patent Office), RP = Reichspatentamt (Patent Office of the German Reich), DP = deutsches Patentamt (German Federal Patent Office), US = United States Patent Office, GB = The (British) Patent Office, F = Office National de la Propriété Industrielle (French patent office), AU = Dept. of Patents of the Commonwealth of Australia, NL = Nederlandsch Bureau voor den Industrieelen Eigendom (patent office of The Netherlands).

Note: in the USA and other countries, a company or business cannot apply for a patent. In such cases, the employee-inventor (i.e., the invention was made as part of the employment) has to apply for the patent (or the patent is applied for in the inventor's name), and then transfer (assign) the patent rights and ownership the employer/company. This assignment transfer is typically done during the application process. An inventor who is not obliged to assign the patent to an employer, may assign his patent (transfer of rights, not of invention) to any other party.

Patent number Patent office Applied Inventor / assignor Patent owner / assignee Title (original, non-English) Title (original English or translated) + brief summary
716134 US 1901 John Stone Stone Whicher, Browne, Judkins (trustees) --- "Method of Determining the Direction of Space Telegraph Signals" [Determination of the bearing of a transmitting radio station by means of a rotable loop antenna (or symmetricall arranged pair of verticals) with which "null" signal direction is found.]
716135 US 1901 John Stone Stone Whicher, Browne, Judkins (trustees) --- "Apparatus for Determining the Direction of Space Telegraph Signals" [Identical to Stone's 1901 US patent 716134.]
770668 US 1903 Alessandro Artom Alessandro Artom --- "Wireless Telegraphy of Transmission through Space" [Generation of a "compact cone" [directional beam] of radio waves, by means of combining 2 or more antennas, transmitting with different phases and directions.]
165546 KP 1904 Christian Hülsmeyer Christian Hülsmeyer (Huelsmeyer) "Verfahren, um entfernte metallische Gegenstände mittels elektrischer Wellen einem Beobachter zu melden" "Method for detecting distant metal objects by means of electrical waves" [This is the invention of radar!]
771819 US 1904 Lee de Forest Lee de Forest --- "Wireless Signalling Apparatus" [Improved, simplified devices for localizing direction of a radio station; rotable antenna (horizontal dipole, horizontal monopole + ground/earth, or vertical loop) + detector/coherer + telephone receiver, with or without battery.]
13170 GB 1904 Christian Hülsmeyer Christian Hülsmeyer (Huelsmeyer) --- "Hertzian-wave Projecting and Receiving Apparatus Adapted to Indicate or Give Warning on the Presence of a Metallic Body, such as a Ship or a train, in the Line of Projection of such Waves" [Expansion of his primary German 1904 radar patent 165546, with closely spaced transmitter & receiver antennas that are shielded from each other, antennas with cardanic suspension to maintain their orientation during ship roll & pitch movements, rotable directive transmit antenna (concave / parabolic reflector) with collocated spark gap, fed with high-voltage via slip rings; receive antenna could also made directive in same direction as transmitting antenna by using reflector.]
25608 GB 1904 Christian Hülsmeyer Christian Hülsmeyer (Huelsmeyer) --- "Improvement in Hertzian-wave Projecting and Receiving Apparatus for Locating the Position of Distant metal Objects" [Expansion of his 1904 British radar patent 13170, with constructional improvements to make elevation angle of the transmision antenna variable, so as to be able to find the azimuth & elevation combination with the strongest reflection from the target. This also allows determination of distance ( = range), as elevation angle is determined and antenna mounting height is know. For ship-mounted installation: mounting on fore deck is limited to 180° sweep due to ship superstructure behind it, so a 2nd transmitter / receiver on the aft deck can expand coverage to 360°.]
833034 US 1905 Lee de Forest Lee de Forest --- "Aerophore" ["radiation concentrating device" (directional transmitter such as spark gap + parabolic reflector) that is slowly rotated by a motor that also drives a "signalling wheel" disk (with dots & dash notches + contact) and a voltage generator + up-transformer + oscillator capacitor; the contact interrupts the voltage to generate high voltage pulses for a spark gap. Sends "code signals" (distinct patterns of several dots and/or dashes) in each azimuth sector. Rotating antenna: parabolic reflector + spark gap, or angled mono-pole  as described in the article "Notizen über drahtlose Telegraphie" ["Notes on wireless telegraphy"] by Ferdinand Braun in Physikalische Zeitschrift, Vol. 4, Nr. 13, 1 April 1903, p. 361-364, which includes §2 "Versuche über eine Art gerichteter Telegraphie" ["Tests with a form of directive telegraphy]).
192524 KP 1907 Otto Scheller Otto Scheller "Sender für gerichtete Strahlentelegraphie" "Antenna arrangement for directional radio transmission" [Multi-antenna systems could not be made directional with spark transmitters, as transmitter output could not be split; patent shows how to do this efficiently with undamped-wave transmitter.]
201496 KP 1907 Otto Scheller Otto Scheller "Drahtloser Kursweiser und telegraph" Wireless course indicator and telegraph. [Invention of overlapping beams with equi-signal; English translation is here.]
378186 F 1907 Alessandro Artom Alessandro Artom "Système évitant la rotation des antennes dans un poste de télégraphie sans fil dirigable et permettant en particulier de déterminer la direction d'un poste transmetteur" "System to avoid rotation of the antennas of a directional radio station and in particular enabling determination of the direction of a transmitter station." [identical to Artom's original Italian patent nr. 88766 of 11 April 1907. Invention of the goniometer, often erroneously attributed to Bellini & Tosi, who lost their case in Italian court against Arthom]
943960 US 1907 Ettore Bellini & Alessandro Tosi Ettore Bellini & Alessandro Tosi --- "System of Directed Wireless Telegraphy" [Antenna configuration with 2 perpendicularly crossing triangular loops (with open top = inverted-U with tips nearly touching), using a goniometer. ([FD = Artom's 1907 French patent 378186) to rotate the antenna system's directivity without physically rotating that system. The 2 antennas are excited by a transmitter such that their radiated fields superimpose and combine.]
11544 GB 1909 Henry Joseph Round Marconi's Wireless Telegraph Co. --- "Improvements in Apparatus for Wireless Telegraphy" [For directional receiving purposes: switched directional beams, here obtained with 2 inverted-L antennas.]
1135604 US 1912 Alexander Meissner Alexander Meissner --- "Process and Apparatus for Determining the Positon of Radiotelegraphic receivers" [Invention of stepwise-rotating-beam Radio Compass beacon. (FD: later referred to as the "Telefunken Compass"; also see equivalent Telefunken's 1912 Dutch patent 981).]
1162830 US 1912 Georg von Arco & Alexander Meissner Telefunken GmbH --- "System for signalling wireless telegraphy under the quenched-spark method" [Improved transmission scheme, with loose coupling between tuned antenna and spark generating circuitry, such that the continous sequence of generated spark oscillations is in sync with the oscillations in the antenna, such that they do not (partially) extinguish one another and a nearly undamped wave results.]
1051744 US 1914 Alexander Meissner Telefunken GmbH --- "Spark gap for impulse excitation" [Pair of round spark-gap plates, one with multiple round dimples (or concentric grooves), the other with mating bumps (or concentric ridges).]
981 NL 1912 - Telefunken GmbH "Inrichting voor het bepalen van de plaats van ontvangers (schepen) door middel van draadloze telegrafie" "Arrangement for position determination of receivers (ships) by means of wireless telegraphy" [Equivalent of Meissner's 1912 German patent 1135604.]
299753 RP 1916 Otto Scheller C. Lorenz A.G. "Drahtloser Kursweiser und Telegraph" "Wireless direction pointer and telegraph" [Expanding his 1907 patent with a radio goniometer to couple transmitter to antenna pair; English translation of the patent claims is here.]
328274 RP 1917 Leo Pungs Leo Pungs "Verfahren zur Feststellung der Richtung eines Empfangortes zu einer Sendestation, von der gerichtete Zeichen ausgehen" "Process for determining the direction of a receiving station relative to a transmitting station that is sending directional signals" [Accuracy of bearing determination with stopwatch of rotating-null beacons that transmit north/south signal (such as Meissner/Telefunken Kompass) depends on synchonicity between beacon & stopwatch. Invention proposes stopwatch with compass degree-scale, two hands/needles, both started simultaneously, one stopped upon reception of first null/minimum, the other upon receipt of second null. In ideal case, angle between the 2 pointers is always 180°. A second, rotable scale is aligned with first pointer and value at second pointer shows bearing correction factor if angle when angle is not 180°.]
130490 GB 1918 Frank Adcock Reginald Eaton Ellis --- "Improvement in Means for Determining the Direction of a Distant Source of Elector-Magnetic Radiation" [Receive only; 2 pairs of vertical dipoles, dipoles of each pair connected with a feedline taht includes 180° twist, in order to suppress received horizontally polarized signals. (FD: this patent is sometimes erroneously attributed to R.E. Ellis, who is actually only the assignee who acted as intermediary / patent agent in the patent application, as the inventor / assignor was serving military duty in WW1 France at that time).]
1301473 US 1919 Guglielmo Marconi, Charles Samuel Franklin Marconi's Wireless Telegraph Co. Ltd. --- "Improvements in reflectors for use in wireless telegraphy and telephony" [For receiving & transmission antenna systems; several reflector configurations, comprising screens of parallel rods, strips, or wires. arranged on a parabolic surface; FD: same as marconi/Franklin's 1919 Australian patent nr. 10922.]
328279 RP 1919 Hans Harbich & Leo Pungs Hans Harbich & Leo Pungs "Schaltung für die Richtungstelegraphie mit Vielfachantennen" "Circuit for directional telegraphy with multi-element antennas" [Antenna ranngement (many crossing dipoles connected to taps on a cylindrical coil winding, with a coaxial rotable second cylindrical coil) usable for transmission and reception; instead of rotating contactor/distributor (subject to contact wear & generating noise during reception) or goniometer (small imbalances cause large large phase shift / detuning, hence requiring very loose coupling), instead proposes tightly coupled transformer coupling with single-point-of-tuning for complete transmitter/antenna system.]
198522 GB 1922 James Robinson & Horace Leslie Crowther & Walter Howley Derriman James Robinson & Horace Leslie Crowther & Walter Howley Derriman --- "Improvements in or relating to Wireless Apparatus" [one or more symmetrical pairs of vertical antennas and feedlines, suppression of transmissioin of horizontally polarized signals of each antenna pair by crossing-over of the feedline at the mid-point between paired antenna. (FD: this is the transmission equivalent of the Adcock's 1918 GB patent 130490]
1653859 US 1923 Ludwig Kühn Dr. Erich Huth G.m.b.H. --- "Apparatus for influencing alternating currents" [Method for AM modulating a continuous RF carrier signal with of iron-core choking coils (several configurations), whose self-inductance is varied with the tone or speech audio signal current.]
252263 GB 1924 Alexander Watson Watt Alexander Watson Watt --- "Improvements in and relating to Radio-telegraphy Direction Finding and other purposes" [Adds CRT display to Adcock's DF antenna system arrangement of GB patent 130490]
475293 RP 1926 Hidetsugu Yagi Hidetsugu Yagi "Einrichtung zum Richtsenden oder Richtempfangen" "Arrangement for directional transmission or reception" [Invention of the "Yagi" / "Yagi-Uda" beam antenna; vertical monopole + ≥1 reflector (≥λ) + ≥1 director (≤½λ), spaced ¼λ); German version of the original 1925 Japanese patent nr. 69115; also see ref. 229H]
1860123 US 1926 Hidetsugu Yagi Radio Corp. of America (RCA) --- "Variable directional electric wave generating device" [Placing a vertical (passive) conductor or antenna at some distance of a likewise vertical main (but energized) antenna, and that passive conductor is resonant at a frequency lower than that main attenna (i.e., is at least ½λ long), then the conductor will reflect the waves of that antenna (project them away), and shape the radiation pattern of that antenna in a directive manner accordingly. Conversely, a conductor with a higher resonant frequency than the main antenna (i.e., is shorter than ½λ) will direct the waves of that antenna in the directions of that conductor. Patent refers to it as a beam antenna. Illustrated with several circular configurations of multiple conductors; also see ref. 229H]
481703 RP 1927 Dr. Max Dieckmann, Dipl.-Ing. Rudolf Hell Dr. Max Dieckmann, Dipl.-Ing. Rudolf Hell Funkentelegraphische Peileinrichtung Direction-finding system for spark transmitter stations [RDF system with stationary loop and a reference antenna, fast switching between antennas, galvanometer "on course" instrument]. Follow-up patent 482281, also 1927, uses pair of switching valves instead of motorized inductive coupler.
1741282 US 1927 Henri Busignies Henri Busignies --- "Radio Direction Finder, Hertian Compass, and the Like" [D/F receive; 2 perpendicularly crossing loops (each with a signal amplifier) + 2-coil galvanometer needle instrument that points at compass scale with 0/90/180/270° ambiguity; ambiguity resolved by slightly rotating the loop's pattern with a servo-driven capacitive goniometer; third config, also to eliminate ambiguity, with separate vertical omni antenna, to yield rotable cardioid pattern).]
632304 F 1927 Alexandre Koulikoff & Constantin Chilkowsky Alexandre Koulikoff & Constantin Chilkowsky "Procédé et dispositifs pour le mesure des distances au moyen d'ondes electro-magnétiques" "Method and apparatus for the measurement of distances by the use of electromagnetic waves" [invention of the radio responder / transponder and distance / range measurement obtained therewith; two receiver / transmitter stations, one initates transmission of a (pulse?) signal. Upon receipt, the second station automatically also transmits a (pulse?) signal (at the same or different frequency). Upon receipt by the first station, the latter automatically again transmits a signal, etc. The resulting back & forth transmissions have a modulation with a beat frequency that is proportional to the distance between the stations. Conversely, in absence of significant time delay between reception and tranmissions, the distance is equal to the speed of light divided by twice the beat-frequency; identical to the1928 GB patent nr. 288233 of the same inventors]
305250 GB 1927 Alexander Watson Watt & Labouchere Hillyer Bainbridge-Bell Alexander Watson Watt & Labouchere Hillyer Bainbridge-Bell --- "Improvements in and relating to Apparatus adapted for use in Radio-telegraphic Direction Finding and for similar purposes" [Expansion of their 1924 GB patent 252263; adds omnidirectional / non-directional sense antenna.]
1937876 US 1928 Eugene S. Donovan Ford Motor Company --- "Radio beacon" [A/N beacon, 2 orthogonal crossing triangular loop antennas (one "A", the other "N"; top/tip grounded, goniometer for rotating combined pattern, remote control, separate low-power transmitter + vertical omni-directional cage antenna for alternating "station indicator" (omni overfly-marker beacon; also to be installed separately along airway) or telegraphy message broadcast; equisignal beam width of 6 miles at 200 miles range (i.e., 1.2°) based on experiments; no specific modulation tone implied]
1831011 US 1928 Frederick A. Kolster Federal Telegraph Co. (part of ITT in 1928) --- "Radio beacon system" [upward beam with hollow conical radiation pattern, in-ground antenna + parabolic reflector; related US patents: 1820004 (1928, Geoffrey G. Kreusi "Aerial navigation system and method"), 1872975 (1928, Frederick A. Kolster "Navigation system and method"), 1944563 (1931, Geoffrey G. Kreusi "Directional radio beam system")]
529891 RP 1928 Alexander Meissner Telefunken GmbH "Verfahren zur drahtlosen Richtungsbestimmung" "Method for wireless determination of direction" [Improvement of Compass with stopwatch, results depend on stopwatch operator and relatively low speed of beacon rotation, hence, requires time-consuming repeated measurements and averageing. Patent: automatic, replace stopwatch with an optical indicator that (somehow...) rotates synchronously with beacon, light pulses light up at 2 spots on compass scale, based on reception of pulses from beacon beam rotating at 10-20 rps (!!!)]
502562 RP 1929 Ernst Kramar & Felix Gerth C.Lorenz A.G. "Verfahren zum Tasten von Richtsendern für rotierende Richtstrahlen" "Method for keying directional transmitters for rotating directional beams" [Using two iron-core choking coils (per Kühn's 1923 German patent 165385, but switching between 0 & 100% saturation, instead of analog modulation) for alternatingly connecting two antennas to a transmitter without using contact-switches or relays]
1941585 US 1930 Eugene Sibley Eugene Sibley --- "Radio beacon system" [A/N beacon with two orthogonally-crosssing rectangular loop antennas, separate synchronized "A" and "N" transmitters. However, not interlcoking A & N Morse characters (and "T" equisignal), but 5-bit Baudot-type encoding of A & N (11000 and 00110 respectively) and K (11110) equisignal. Combined with a "Teletype" keyboard teleprinter system for transmitting the (adjustable) beacon course to the pilot via the beacon's directional loop antennas, or course, weather and other broadcast info, via the non-directional marker of the beacon station or en-route marker beacons. Automatic compact "Teletype" tape printing telegraph in the cockpit. Demonstrated.]
546000 RP 1930 Meint Harms Meint Harms "Verfahren einer selbsttätigen Ortsbestimmung beweglicher Empfänger" "Method for position finding by a mobile receiver" [Invention of hyperbolic radio navigation; autonomous localization of a moving receiver by using 2 (or more) coherent CW transmitter stations with spacing equal to integer multiple of the wavelength. One station acts as master, with stable phase, the second is synchronized to it and transmits on 2x the Master frequency (or, in general, any frequency that is coherent with the Master's) without phase shift. Receiver has 2 antennas, one for the Master frequency, the other for the Slave frequency. The receiver amplifies both signals separately, while at the same time doubling (or whatever the coherent Amster-Slave frequency factor is) the frequency of the Master's CW signal. The 2 resulting same-frequency CW signals are combined/compared, and the result drives an electro-mechanical up/down counter. Starting at a know position, each time movement causes Master-Slave phase difference to make a 360° → 0° transition, the counter value is changed in one direction, and in the opposite direction upon each 0° → -360° transition. So, during movent along a 0° phase difference hyperbel, the counter vale is not changed (FD: i.e., counter value change corresponds to 1λ hyperbel change).]
363617 GB 1930 Reginald Leslie Smith-Rose & Horace August Thomas Reginald Leslie Smith-Rose & Horace August Thomas --- "Improvements in or relating to Wireless Beacon Transmitters"  [Rotating beacon, 6-10 ft square loop antenna, rotating about a vertical axis at 1 rpm; transmitting a characteristic signal when passing the geographical meridan [ = north/south direction], receiver uses stopwatch to measure time between passage of reference signal and signal's minimum-intensity passage; vertical loop or inclined loop with suppression of non-horizontal radiation; also covers version comprising 2 pairs of vertical antennas with a goniometer with 1 stator and 2 rotors.]
661431 RP 1930 Ernst Kramar C. Lorenz A.G. "Einrichtung zur Richtungsbestimmung drahtloser Sender" "Arrangement for direction finding of wireless transmitters" [Apparent width/sharpness of "A/N" (or similarly complementary keyed) equisignal beam, depends on accuracy of the A/N signal-strength comparing electronic instrumentation that is used for determining course deviation, esp. for visual indicator. Constant two-tone instead of A/N keying system requires accurate tone filtereing and high signal strength and/or high-gain reed-instrumentation. Significant improvement of sensitivity / apparent beam-sharpness by using (diode tube) rectifiers with quadratic characteristic, to increase the apparent relative signal strength of the received 2-tones.]
2014732 US 1930 Clarence W. Hansell Radio Corporation of America (RCA) --- "Radio beacon system" [3 crossing rectangular loop antennas (or 3 vertical antennas on corners of triangular footprint) + 1 vertical omni-directional antenna at center; cardiod pattern; transmitter = crystal controlled carrier-frequency generator + modulator + "modulating wheel" tone generator driven by synchronous motor (continuously variable pitch = FM modulation with tone "chirp": 2 Hz sawtooth signal with 150-250 Hz linear tone ramp) + 4 amplifiers (1 for each of 3 loops/verticals, 1 for central vertical omni antenna). Synchronous 2 rpm motor also drives goniometer to continuously rotate the cardiod pattern. Receiver audio output is fed to a circular indicator with 36 reeds, each tuned to a tone in the 150-250 Hz range. Patent claims system was actually demonstrated.]
349977 GB 1930 John M. Furnival, William F. Bubb Marconi's Wireless Telegraph Co. Ltd. --- "Radio beacon" [2 orthogonal crossing triangular loop antennas + goniometer; cam-driven callsign/identifier Morse code; standard 2 or more adjustable equisignal directional zones (e.g., cam-driven A/N system), and rotating directional signal/beam (cardioid or figure-of-8 using same 2 loop antennas) with predetermined speed + omni-directional reference direction marker (e.g., north passage ID), i.e., the 1912 Telefunken/Meißner system per German patent 1135604]; same as the Furnival/Bubb US patent 2045904 filed a year later (in 1931), which has, however, Radio Corporation of America (RCA, originally Marconi's Wireless Telegraph Co. of America, "American Marconi") as assignee/owner.
1945952 US 1930 Alexander McLean Nicolson Communications Patents, Inc. --- "Radio Range Finder" [One of the stations initiates an RF carrier impulse of predetermined duration (e.g., 10-100 cycles of a 1 MHz carrier). The receiver of the second station (referred to as "reflecting" station) keys the associated transmitter for the duration of the received pulse. The resulting is received back at the initiating station, after round-trip travel time at the speed of light. That time is proportional to twice the distance between the stations. Like the second station, the receiver in the initiating station now keys the associated transmitter for the duration of the received pulse. This results in continuous back-and-forth transmissions. The resulting beat-frequency indicated on a meter instrument with distance scale. (FD: this method is a copy of the one in the 1927 Koulikoff & Chilkowsky responder/transponder patents FR632304 and GB288233!) In a second embodiment of the method, a manually variable re-transmission delay is used in the originating station is used, which is adjusted until the circulating beat frequency is zero. Patent claims that meter or audible tone may also indicate direction of travel. However, it can only do so in the sense of increasing or decreasing distance (i..e, not bearing)! ]
1949256 US 1931 Ernst Kramar C. Lorenz A.G. --- "Radio Direction Finder" [Visual course-deviation indicator/meter with dial/scale, for use with an equi-signal beam fixed course-beacon (e.g., A/N, or easier to interpret by pilot: E/T = dot/dash). Four embodiments (circuit diagrams) shown, all transformer-coupled audio output of receiver, a rectifier (tube/valve) with quadratic characteristic (to obtain high gain for small differences), and a galvanometer. The meter-needle swings about the non-zero deflection corresponding to the equi-signal, in the rhythm of the received dots & dashes, and the swing amount depends on the relative strength ( = course deviation direction and amount). Note: this is not a "kicking meter" arrangement, in which dot/dash pulses are passed through an inductive differentiating circuit, and meter deflection is about the zero indication. Also proposes transmitter keying not with square pulses, but rounded pulses with "rapid rise"/"slow decay" pulse flanks for one of the two overlapping beams, and the opposite for the complementary beam.]
1923934 US 1931 Frank G. Kear US Government --- "Radio beacon course shifting method" [shift 2 beacon courses from their normal 180° displacement to align them with 2 airways that intersect at an angle other than 180°; expand 2-loop/2-pair antenna config with separate vertical antenna (inductively coupled to one of the goniometer primaries) whose omni-directional patternn combines with the figure-8 of 1 loop to create a cardioid.]
1992197 US 1932 Harry Diamond US Government --- "Method and apparatus for a multiple course radiobeacon" [rapid increase in number of airways emanating from major airports means need beacon capable of marking > 4 courses; 3-tone beacon with up to 12 simultaneous courses; 2 triangular vertical loops crossing at 90°, several transmitter configurations (transmitter with master oscillator (carrier freq) + 3 intermediate modulator-amplifiers (65, 86⅔, 108⅓ Hz tones) + 3 final amplifiers, special goniometer with 3 stators (1 for each PA, spaced 120°) + 1 rotor (2 coils crosssing at 90°, each coil 3 sections); several other transmitter configurations.]
1913918 US 1932 Harry Diamond & Frank G. Kear US Government --- "Triple modulation directive radio beacon system" [expansion of H. Diamond triple-modulation/12-course beacon system 1932 US patent 1992197, same diagrams, adding method for shifting the normally 30°-spaced individual courses of the 12-course beacon, to align them to the airways.]
577350 RP 1932 Ernst Kramar C. Lorenz A.G. "Sendeanordnung zur Erzielung von Kurslinien" "Transmission arrangement for creation of course lines" [This is the invention of what was later called the "Lorenz Beam", localizer part of the Instrument Landing system; create equisignal beam, not with two separate directional antenna systems with overlapping patterns, but with a single omnidirectional vertical dipole antenna whose continuously active circular pattern is alternatingly deformed into a bean-shaped pattern to the left and right, by activating a corresponding parallel vertical reflector ( = passive) that is placed at some distance to the right & left of the vertical antenna. The two reflectors are alternatingly enabled in the standard A/N or similiar dots/dashes rhythm. The shape of the "bean" patterns depends on the length of the reflector rods and the distance between the reflectors and the dipole antenna. This method also eliminates key-clicks, since the vertical dipole is allways energized (i.e., not keyed).]
592185 RP 1932 Ernst Kramar & Felix Gerth C. Lorenz A.G. "Gleitwegbake zür Führung von Flugzeugen bei der Landung" "Glide path beacon for guiding airplanes to landing" [Blind/fog landing requires localizer/course beam and glide-path guidance. The latter follows the curved constant-field-strength path upon beam intercept. So far, ground stations used a LW localizer beam and separate VHF glide path beacon. This requires two complete beacon transmitter and receiver systems. Patent proposes simplification by using a single VHF equisignal beam beacon system with complementary keying (with choking-coils; FD: see Kühn's 1923 US patent 1653859 and Karmar/Gerth's 1929 German patent 502562) with asymmetrical pulses (short-rise/long-fall times for one beam and the opposite for the other beam; here: triangular pulses (FD: Kramar's patent 1949256 proposes rounded pulses). The VHF receiver's audio output is rectified. The rectifier output is fed to a galvanometer that indicates the combined/summed strength of the two beams, and is used to fly a constant-strength curved glid path. The rectifier output is also transformer-coupled to a push-pull amplifier stage that drives a kicking-meter (alternatively, the rectifier output can feed a differential-galvanometer). This meter indicates course deviation.]
405727 BP 1932 --- C. Lorenz A.G. --- "Directional radio transmitting arrangements particularly for use with ultra-short waves " [Same as Lorenz' 1932 German patent 577350]
589149 RP 1932 --- C. Lorenz A.G. "Leitverfahren für Flugzeuge mittels kurzen Wellen, insbesondere ultrakurzer Wellen" "Method for guiding aircraft by means of short waves, in particular ultra-short waves" [Landing beacon arrangements to accommodate final descent to a landing from various heights, in particular steep descents from higher altitudes, and glide path intercept (FD: from below = the way it shoud be done) from greater distance. One arrangement with standard Lorenz course beacon ( = vertical dipole + 2x reflector) placed at the approach end (!!!!) of the runway (serving as course beacon and runway marker beacon), and a standard equisignal glide path beacon placed at the departure end (!!!) of the runway. By using different modulation tones, both could operate on the same frequency (in particular with appropriate tone filters at the receiver). Other arrangement with two co-located standard Lorenz course beacons side-by-side, the plane of the antenna systems of these beacons at an appropriate elevation angle instead of vertically (to generate glide path beam of 8-11° (FD: vs. 3° standard in modern times), and at an angle with respect to each other such that their equisignal beams cross; slightly expanded by Lorenz' same-title 1933 German patent 607237.]
1961206 US 1932 Harry Diamond US Government --- "Twelve-course, aural type, triple modulation directive beacon" [Explicitly aural beacon ( = requires interpretation of 3 audio tones (e.g., 850, 1150, 1450 Hz) by pilot, i.e., not 12-course VISUAL beacon with visual instrument to interpret the tones; Aural 12-course beacon were considered impossible, as for 6 of the 12 courses, the 2 overlapping tones that form the equi-beam are overpowered a much stronger figure-8 lobe of the 3rd tone; LW (e.g., 290 kHz) transmitter blockdiagram for 2 configs; keying device between modulators with slip contacts on rotating cylinders with patterns of conductive patches)pilot selectable audio filters.]
2093885 US 1932 Ernst Kramar & Felix Gerth Standard Elektrik Lorenz A.G. --- "Means for guiding aeroplanes by radio signals"  [Two overlapping VHF beams for lateral guidance, curved glidepath on constant signal strength of same 2 beams; FD: equivalent to Lorenz' 1932 German patent 592185.]
408321 BP 1932 --- C. Lorenz A.G. --- "Radio beacon for directing aircraft" [Two overlapping VHF beams for lateral guidance, curved glidepath on constant signal strength of same 2 beams; FD: equivalent to Lorenz' 1932 German patent 592185.]
2028510 US 1932 Ernst Kramar C. Lorenz A.G. --- "Transmitter for electromagnetic waves" [FD: equivalent to the 1932 German "Lorenz Beam" patent 577350.]
1981884 US 1933 Albert H. Taylor, Leo C. Young, Lawrence A. Hyland Albert H. Taylor, Leo C. Young, Lawrence A. Hyland --- "System for detecting objects by radio" [Detection of moving objects (e.g., aircraft, ship, motive vehicle), system comprising CW transmitter and remotely located receiver, continuously receiving ground waves directly from transmitter (constant signal), and intermittently receiving skywaves that are not reflected (!!!) but re-radiated by such conductive/metallic objects (or parts thereof) that have a size of ca. ½λ of the transmitted CW signal, and that interfere/combine with the ground waves signals (causing variable amplitude at receiver). Amplitude of the interence pattern signal fluctuates when object moves, more rapidly (and with larger amplitude) when moving over receiver or transmitter site. Also, moving parts of the object (e.g., rotating propeller(s) = "propeller effect"), cause superimposed distinguishable modulation of the interence pattern signal. Ground wave may be extinguished by the time it reaches receiver, or be transmitted in dirction of receiver if using directional transmitter.]
2121024 US 1933 Harry Diamond US Government --- "Radio transmitting and receiving system" [System for simultaneous transmission of radiotelephone (e.g., broadcast of weather & landing conditions) and radio range beacon signals. For some time, these 2 radio services used different radio frequencies; due to expansion of beacon network, frqeuencies becoming scarce. Method for simultaneous transmission, without overlapping modulations. 2 loop antennas for beacon service, separate omni antenna for broadcast service; single master RF oscillator for both services, with 3+1 intermediate modulator amplifiers (3 keyed tones + microphone or recorded message), and 3+1 final amplifiers; 2-outputs tone filter unit between receiver and headphones, with LPF for beacon signals and HPF for broadcast audio.]
2172365 US 1933 Harry Diamond US Government --- "Directive antenna system" [Radio range beacon; to eliminate erroneous course indications with crossing loop beacons due to "night effect", now antenna configuration with 2 pairs of 2 vertical antennas, evenly spaced, each with ground plane, all with same feedline distance to transmitter, coupled to a single transmitter via a radio goniometer and tuned feedlines to a coupling transformer for each antenna pair, with 180° twisted feedline between on the antenna side of these transformers. Refers to patents GB130490 (1919), GB198522 (1923), and GB363617 (1932).]
1999047 US 1933 Walter Max Hahnemann C. Lorenz A.G. --- "System for landing aircraft" [Upon intercept, as indicated on meter, the pilot adjusts vertical flight path as necessary, such that the meter deflection does not change from the indication at moment of intercept (absolute deflection is not important). Various converging curves can be selected ( = steepness), by adjusting the receiver/indicator gain, also possible a receiver device that is triggered by reception of the marker beacon and with a timer, moves the indicator scale to indicate estimated height above ground.]
2348730 US 1933 Francis W. Dunmore & Frank G. Kear US Government --- "Visual type radio beacon" [Fixed course beacon comprising 2 pairs of "transmission line" (TL) antennas (pair of vertical monopoles with ground planes, instead of 2 crossing loops) with figure-8 pattern (90° phase shifted excitation), with a different modulation tone (65 & 83⅔ Hz) for each pair (feed-line arrangement to eliminate "night effect"), combined with two co-located omni-directional transmissions on same frequency but with 270° phase difference, with the same 2 modulation tones; combined "figure-8 and omni" pattern pairs form cardioid pattern; two 2 overlapping cardioids form 2 equisignal course lines; refers to description in CAA-ACM 1932 No. 2.]
653519 RP 1933 --- Marconi's Wireless Telegraphy Co. Ltd. "Verfahren zur Übermittlung von Nachrichten allert Art auf drahtlosem Wege" "Method for wireless transmission of messages" [directly readable, omni-directional transmission of, e.g., weather data, as pointer on CRT display with scale, without synchronization complexity of TV or fax]
2072267 US 1933 Ernst Kramar C. Lorenz A.G. --- "System for Landing Aircraft" [Expanded by 1937 follow-up Lorenz' 1937 US patent 2215786 "System for landing airplanes".]
2120241 US 1933 Harry Diamond & Francis W. Dunmore US Government --- "Radio guidance of aircraft" [UHF landing/take-off beam beacon, method and apparatus, able to serve all wind directions with a single beacon that has variable glide path steepness to a proper/predefine touch-down point. Demonstrated at College Park/MD and Oakland/CA airports. Beacon antenna placed in a pit, just below ground level of the airfield / landing zone. First antenna arrangement: horizontal UHF dipole. With this installation position, the dipole's torus radiation pattern in free space (FD: i.e., figure-8-on-its-side vertical cross-section in all directions) is pushed upward with increasing distance from the antenna, enabling curved constant-field-strength glide path. The horizontal dipole can be made rotable about its vertical axis (with remote controlled motor and 2 slip rings to feed the antenna) to accomodate any pair of 180° spaced directions (2-course). A rotable 4-course equivalent can be obtained by using two crossing dipoles with 2 pairs of slip rings.]
2044852 US 1933 Ernst Kramar C. Lorenz A.G. --- "Electric indicator for comparing field intensities" [E/T equisignal beam deviation indicator; standard circuitry with rectifier and transformer; galvanometer. References 1928 US patent 1782588 "Electrical mesasuring instrument" (2-pole galvanometer with rotary coil) by F.E. Terman. The desrired meter sensitivity reduction for increasing meter / needle deflection is obtained electromechanically instead of electronically, by tapered (instead of concave) shape of the galvanometer poles.]
616026 RP 1934 --- C. Lorenz A.G. "Sendeanordnung zur Erzielung von Kurslinien gemäß Patent 577 350" "Transmission arrangement for obtaining course-lines per Lorenz' 1932 German "Lorenz beam" patent 577350" [vertical dipole + two near-resonant reflectors]
612825 RP 1934 --- C. Lorenz A.G. "Verfahren zum Betrieb von Funkbaken" "Method for operating a radio beacon" [2-course A/N or E/T beam; left/right beams are swapped, based on which of the two courses is actively used by aircraft, such that indicated left/right course deviation indications is correct for both, i.e., A & N (E & T) always on the same side of the equisignal beam when approaching the beacon]
2196674 US 1934 Ernst Kramar & Walter Max Hahnemann C. Lorenz A.G. --- "Method for Landing Aircraft" [Localizer beacons that are used to provide guidance for curved, constant field-strength approach to landing, typ. depend on constant transmitter power and constant receiver gain (FD: at least during the beam intercept and final approach & landing phase). The latter is more difficult to ensure than the prior. Method usable with equisignal course beam beacons, elevated/upwardly transmitted radiation patterns, and torus-shaped patterns (FD: e.g., from a vertical dipole or monopole). Method uses a marker beacon (accoustic or - preferred - radio) below the intended point of positive intercept of the desired constant field-strength curves. This also supports using the same curve, even if intercepting at a different altitude. Aircraft to approach & intercept the beam (FD: from below) at a predermined altitude. The marker beacon may transmit vertically or at some other, steep elevation angle in te direction of the approach. Upon intercept, as indicated on meter, the pilot changes vertical flight path such that the meter deflection does not change from the indication at moment of intercept (absolute deflection is not important). Various converging curves can be selected ( = steepness) with method covered by Hahnemann/Lorenz' 1933 US patent 1999047. Patent also references Kramar/Lorenz' 1932 US "Lorenz Beam" patent 2028510]
2217404 US 1934 Walter Max Hahnemann & Ernst Kramar C. Lorenz A.G. --- "System and Method for Landing Airplanes" [Expansion of Hahnemann/Kramar 1934 US patent 2196674 with the manually adjusted receiver/indicator configurations per Fig. 4 & 5 of Hahnemann's 1933 US patent 1999074]
2025212 US 1934 Ernst Kramar C. Lorenz A.G. --- "Radio Transmitting Arrangement for Determining Bearings" ["Lorenz Beam" beacon station with continously rotating equisignal beam course direction. Standard antenna arrangement (continously excited vertical dipole (with omni pattern), a vertical reflector on each side, motorized A/N keying for complementary reflector interruption). However, now with the reflectors continously rotating about the vertical dipole, with the relays used to interrupt each reflector controlled via slip rings, to create a rotating 2-course equisignal beam system. This is much simpler than an arrangement with a motorized radio goniometer. During passage of the equisignal beam pair through a predetermined bearing (e.g., north/south), the interruption of the reflectors is briefly stopped and a predetermined combination of Morse characters is omni-dirctionally transmitted via the vertical dipole (keying by hand or motorized). receiver station determines bearing to/from station based on timing beam passage after "north" signal (FD: = Telefunken Compass stopwatch method). Alternatively, a short special character (e.g., a single dot) could be tranmsitted omnidirectionally at regular bearing increments (e.g., every 5°), and the receiver's bearing be estimated simply by counting the number of received dots since the north/south signal reception]
2083242 US 1935 Wilhelm Runge Wilhelm Runge --- "Method of Direction Finding" [3D RDF method, searching direction with maximum signal strength (unlike minimum method, accuracy is not affected by background noise, static, etc.) with a highly directional antenna system; antenna beam is moved, such that its narrow/sharp beam is precessed (conical movement) about a pointing direction (without changing the polarization direction of the antenna). Beam precession is obtained either mechanically (precession manually or with motor drive, and receiving dipole with a parabolic reflector, on a platform with manual or motorized rotation about vertical axis to change bearing, manual elevation axis adjustment; adjustments until strength of received signal remains constant (FD: this is referred to as "hill climbing" technique in modern control systems engineering terminology), or electrically (a stationary "flat" symmetrical 2D array of dipoles, with beam sweeping by means of changing phases (feed line lengths) between the dipoles.]
2184843 US 1935 Ernst Kramar C. Lorenz A.G. --- "Method and Means for determining Position by Radio Beacons" [Method of determining bearing at the receiving station, automation of this method, for use with rotating equisignal beam beacon with 1) E/T keying (60 per 360° rev of the beacon = 15 per quadrant = 1 per 6° rotation), 2) omni-directional transmission of sync/timing/zero signal upon beam passage through specific direction (e.g., north), and 3) beam transmission only during the first 180° rotation after the sync signal; standard "kicking meter" differentiating circuitry (transformer) for converting leading & trailing edge of received E & T tone pulses into short voltage peak pairs (polarity sequence +/- for E, -/+ for T); these + & - peaks are counted separately with 2 electro-mechanical counting devices; stopwatch-type bearing indicator that is reset & started manually or automatically based on receipt of the omni "north" signal) and stopped automatically by the counters upon detection of the equibeam signal; bearing ( = angle from the sync signal) is difference in number "a" of dots and number "b" of dashes reecived between the sync signal and equisignal beam passage, multiplied by half the number "f" of dots & dashes per 360°, i.e., (a-b)*(f/2).]
180995 CH 1935 --- C. Lorenz A.G. "Sendeanordnung zur Erzielung von Kurslinien mittels zweier verschieden gerichteter, abwechselnd asugesandter Hochfrequenzstrahlungen" "Transmission arrangement for generating course lines bei means of two high frequency fields, alternatingly sent in two different directions"  [standard Lorenz landing beam beacon = vertical dipole + 2 alternatingly switched parallel passive reflectors, E/T = Dot/Dash keying]
180996 CH 1935 --- C. Lorenz A.G. "Verfahren zum Betriebe von Funkbaken" "Process for operating radio beacons" [standard Lorenz landing beam beacon = vertical dipole + 2 alternatingly switched parallel passive reflectors, E/T = Dot/Dash keying, but two sets of outer & inner marker beacons (on front course & back course); to avoid confusion interpreting inverted left/right meter deflection on front course vs backcourse, keying of the reflectors can be inversed, depending on which equisignal course the inbound aircraft is using.]
44879 F 1935 --- C. Lorenz A.G. "Appareil transmetteur pour les ondes électriques et en particulier pour les ondes ultra-courtes" "Transmitter for electrical waves, in particular ultra-short" [A vertical dipole at an appropriate height above ground has a radiation pattern that resembles a torus (ring) that is slightly angled upward, away from the antenna (as opposed to a perfect torus when in free-space), instead of a perfect torus if that dipole were in free space. Likewise, if the dipole pattern is deformed with a vertical deflector. Thus upward angle makes it possible for the same beacon to provide glide path guidance. Localizer beacon placed at standard position (on the landing course-line, beyond departure end, and outside the boundary of the airfield (FD: in those days, airfields were often round, without runways). Lines of constant equisignal field-strength emanate from the beacons antenna system, curve downwards towards ground level over some distance, then curve upward with increasing distance. No radiation straight up (FD: i.e., the "hole" in the torus). Pilot follows equisignal localizer beam inbound at the certain altitude, until intercepting a particular curved constant-strength line (or receiving the signal from a marker beacon placed on the course line), and then descends to landing, ensuring that the indicated signal strength remains constant, i.e., the aircraft follows the associated curved line (glide path). Similar to Kramar/Hahnemann's 1934 US patent 2196674.]
2134535 US 1936 Wilhelm Runge Telefunken GmbH --- "Distance Determining System" [Based on received signal-strength. Method depends on receiver sensitivity and transmitter power. Distance is derived from signal strengths received by 2 antennas installed at the same location but a different heights above ground/sea. In general at VHF and horizontally polarized waves, received field intensity is zero at zero height, and changes in sinusoidal manner with increasing height, due to interference of slanted direct wave and ground-reflected wave (single "bounce"). Path-length difference between those waves is equal to 2x product of the transmitter & receiver antenna height, divided by distance over ground level. Receiver audio level is proportional to square of field strength. For known transmit & receive antenna heights + audio volume ratio of the 2 receive antennas, a formula for distance-over-ground is derived.]
2117848 US 1936 Ernst Kramar C.Lorenz A.G. --- "Direction Finding Method" [D/F antenna and circuitry arrangement to produce 2 alternating/opposed cardioid patterns. Instead of standard arrangement of two loop antennas that are alternately combined with an omni-directional antenna, or of single loop with alternatly used center tap: loop antenna + 2 omni antennas, one of which generates 2x the signal strength as the other and with opposite sign, all 3 antennas coupled to the input tube of the same receiver. The "2x" omni antenna is connected via variable coupling, to create a rotable cardioid. Same antenna is activated with switch, typ. in rythm with 50% on/off duty cycle.]
2170659 US 1936 Ernst Kramar C.Lorenz A.G. --- "Direction Finding Arrangement" [D/F antenna and circuit arrangement, with alternately connecting 2 loop antennas with opposite sense of winding (and directivity), switching controlled by a motorized commutator, aural output and visual indication to pilot/operator (the latter in the form of a signal-strengths comparing indicator per Kramar's 1933 US patent 2044852).]
2141247 US 1936 Ernst Kramar & Heinrich Brunswig C.Lorenz A.G. --- "Arrangement for Wireless Signaling" [References Kramar's 1932 US patent 2028510, which itself is equivalent to Kramars 1932 German "Lorenz Beam" patent 577350, as baseline for the antenna arrangement of 1 vertical dipole + 2 switchable reflectors (FD: resulting plane measures ca. ½λ x ½λ). The physical length of the dipole and the reflectors is reduced significantly (e.g., to 1/8 λ or 1/3 λ), and the associated reduction in electrical length is compensated by adding inductances (FD: "loading coils"). The omni-directional radiation pattern of the dipole is hardly affected by shortening the dipole, as well as by the angles of intersection between the two overlapping beams. If the electrical length of the reflectors is also reduced, and compensated back up to ¼λ or ½λ, the patterns becomes more cardioid than that of the baseline arrangement. (FD: ¼λ spacing must be retained for the reflectors to work as such). Principle of the patent is applicable to directional reception and transmission. ]
734130 RP 1937 Ernst Kramar & Walter-Max Hahnemann C.Lorenz A.G. "Ultrakurzwellen-Sendeanordnung zur Erzielung von Gleitwegflächen" "Arrangement of VHF transmission for generation of glide path planes" [Curved "constant field strength" glide path: curve to be used (FD: steepness & gradient) depends on aircraft type (approach speed, etc.). If beacon beyond departure end of runway, then beam elevation adjusted such that flat bottom of curves coincides with intended touch-down point. More optimal curve(s) obtained when curve bottom coincides with ground level at the beacon location. This requires beacon installation at the intended touch-down point. E.g., 2 UHF beacons with horizontal diople just below ground level at the intended touch-down point (FD: i.e., per Diamond/Dunmore's 1933 US patent 2120241). Straight glide path guidance can be obtained with equisignal beam, e.g., two VHF dipoles below ground (fed in-phase by common transmitter), spaced several wavelengths on the localizer course line. Also see equivalent Hahnemenn/Kramar 1939 US patent 2210664]
816120 FR 1937 Le Matériel Téléphonique S.A. Le Matériel Téléphonique S.A. "Systèmes de guidage par ondes radioélectriques par exemple pour l'atterrissage des avions sans visibilité extérieure" "Radio guidance systems, e.g., for landing aircraft without external visibility" [Antenna arrangement for creating 2 overlapping beams with equisignal zone, front-course only, no significant back-course beams (i.e., 1-course, not 2-course pattern). Hence, no ground & obstacle reflections from the back-course emissions. arrangement with vertical dipole + reflector at ¼λ + 2nd vertical dipole (or director) at ½λ + side-reflector at ¼λ, transmitter located behind the reflector (in the now suppressed back-course zone). Two such arrangements to obtain the 2 overlapping beams. Vertical (glide path) guidance via standard visual/instrument method (curve of constant field-intensity), enhanced with device that converts signal strenght to audio tone frequency, hence, deviation from constant field-strength curve changes the audio pitch.]
2147809 US 1937 Andrew Alford Mackay Radio & Telegraph Co. --- "High frequency bridge circuits and high frequency repeaters"  [transmission-line bridge to combine two tone-modulated RF signals with same carrier frequency; used on 90/150 Hz Localizer and Glide Slope systems]
705234 RP 1937 Ernst Kramar & Dietrich Erben C.Lorenz A.G. "Sendeanordnung zur Erzeugung von geknickten Kurslinien" "Arrangement for generating angled/bent course lines" [In the standard configuration of equisignal beam beacon with 1 vertical dipole + 2 alternately switched vertical reflectors (FD: i.e., "Lorenz Beam"), is with reflectros spaced symmetrically left & right of the dipole. Resulting radiation pattern has 2 equisignal beams that point in opposite directions. Beam directions can be shifted to obtain angles other than 180°/180° ((FD: this is referred to as "course bending"), by spacing the reflectors asymmetrically with respect to the dipole. Extreme case of using dipole with single reflector also has this effect, but makes equisignal beam unsharp. Alternative configuration is vertical dipole with symmetrically spaced reflectors, but reflectors of unequal length, one ½λ and the other < ½λ (FD: i.e., 1 reflector + 1 director).]
720890 RP 1937 Ernst Kramar & Werner Gerbes C.Lorenz A.G. "Anordnung zur Erzeugung einer geradlinigen Gleitwegführung für Flugzeuglandezwecke" "Arrangement for generating straight glide path guidance for aircraft landing purposes" [Curved "constant field-strength" beacon glide paths are generally (too) steep on approach and (too) flat near ground, resulting in (too) high landing speed and associated extended floating before actual touch-down. (FD: also require constant power controls and pitch angle adjustments by pilot, instead of stabilized approach, which is highly undesirable and bad practice). A (near-)straight glide path guide beam can be obtained with an upwardly angled equisignal beam (of two vertically overlapping complementary keyed beams, instead of using curves of horizontally overlapping beams). Optimal equisignal beam elevation angle is ca. 3°. High sensitivity for glide path deviation indication requires very sharp/directive sub-beams. For practical antenna system dimensions, this implies UHF radio frequencies (freq. > 300 MHz = wavelenghts < 1 mtr); multiple equisignal beams (at separate elevation angles), separated by sharp nulls, are obtained when antenna system placed several wavelengths above ground. No problem, if always intercepting the equisignal beams from below. So far, nothing new. Proposed antenna configuration: two stacked vertical collinear dipoles. A/N keying makes it possible to identify the multiple glide slope (GS) beams, as the "A" & "N" sub-beams are above/below the lowest GS beam, below/above the next (steeper) GS beam, etc. Same beam patterns can also be obtained with a single vertical antenna that is several wavelengths long (FD: to obtain pattern with multiple lobes), the electrical length of which is cyclicly momentarily slightly increased in the standard complementary keying rythm. Also see Kramar's 1938 US patent 2297228]
2215786 US 1937 Ernst Kramar & Walter Max Hahnemann C.Lorenz A.G. --- "System for landing airplanes" [Partial continuation of Kramar/Hahnemann's 1934 US patent nr. 2196674. Known is VHF beacon with upwardly-angled omni-directional torus-shaped radiation pattern, creating constant-signal-strength glide path curves. This required constant transmitter output and constant receiver gain during the landing phase. Patent proposes using one or more marker beacons, with narrrow pattern across thee approach course line, to indicate glide path intercept planes, and starting point for following constant-signal-strength glide path. (FD: no significant expansion of the referenced 1934 patent).]
2226718 US 1937 Ernst Kramar & Walter Max Hahnemann C.Lorenz A.G. --- "Method of Landing Airplanes" [Continuation of Kramar/Hahnemann's 1934 US patent nr. 2196674 and their 1937 US patent 2215786. ]
767399 RP 1937 Ernst Kramar & Joachim Goldmann C.Lorenz A.G. "Verfahren zur Erzeugung einer vertikalen Leitebene" "Method for creating a vertical guidance plane" [Method for long-range navigation; standard beacon with two complementary-keyed (e.g., A/N) overlapping beams with associated equisignal beam course-line, operating on Longwave or VHF frequencies, suitable for short-range; very long range navigation (great-circle) requires short-wave frequencies; on short-wave, radio waves propagate as groundwaves and skywaves. The latter are refracted by E &amp; F layer in ionosphere, depending on wave elevation angle and frequency. At the receiver station, these various waves combine / interfere; associated phase differences cause periodic fading and A/N distortion, affecting apparent course line. Solved with elevated directional beams (3 parallel vertical dipoles one 1 line + 2 reflectors on perpendicular line through center dipole), such that received skywave is always stronger than the groundwave. Antenna arrangement can be made azimuth-rotable. References Hahnemann's 1924 German patent 474123, Yagi's 1926 German patent 475293, and LMT Co.'s 1937 French patent 816120.]
2206463 CH 1938 --- C. Lorenz A.G. "Sendeanordnung zur Erzielung von Kurslinien" "Transmission arrangement for generating course lines" [Simplified Lorenz landing beam system; vertical dipole with single periodically activated parallel passive reflector.]
731237 RP 1938 Ernst Kramar C.Lorenz A.G. "Empfangsverfahren für Leitstrahlsender" "Method of reception of guide beam beacons" [Method for obtaining simultaneous aural & visual indication regarding equisignal beam of beacons with two overlapping-beams that are complementary-keyed with two different modulation tones. At receiver, the 2 tones are separated with 2-channel filter unit, rectified and fed to a comparing visual instrument. Beacon also broadcasts its keying signal via separate modulaton frequency. This is also received, and used to drive a commutating relay (i.e., synchronized to the beacon keying) for passing the filtered received tones to circuitry that generates their harmonics that are modulated such that the 2 complementary keyed tones now have the same audio frequency (i.e., as if the beacon was a standard 1-tone complementary-keyed one), and fed to the headphones. Also see Kramar's equivalent 1939 US patent 2255741]
206464 CH 1938 --- C. Lorenz A.G. "Rotierende Funkbake" "Rotating radio beacon" [Motorized rotating antenna arrangement of 2 pairs of vertical antennas (grounded monopoles or dipoles) at corners of a square, Adcock arrangement, simultaneously fed by transmitter via , central vertical monopole, fed simultaneously by same transmitter; creates rotating equi-signal beams; using shortwave to obtain long range]
767522 RP 1938 Ernst Kramar & Felix Gerth & Joachim Goldmann & Heinrich Brunswig C.Lorenz A.G. "Empfangsvorrichtung zur Richtungsbestimmung mittels rotierender Funkbake" "Receiving device for determining direction with a rotating radio beacon" [Rotating-beam beacon with omnidirectional north-signal pulse and rotating minimum/null; mentions optical device with synchronously rotating light bulb (inaccurate, complicated construction) and CRT display (Braunsche Röhre) showing pip upon receipt of max signal]
711673 RP 1938 Ernst Kramar C.Lorenz A.G. "Gleitweglandeverfahren" "Glide Path Landing Method" [The curved/parabolic constant-field-strength VHF glide paths are too steep at altitude and too flat near ground (with high engine power setting, resulting in floating down the runway due to high speed), which cannot be done with all aircraft type. Beam method provides (near-)straight glide path (FD: i.e., glide slope), allowing descent to landing with constant descent rate ( = constant vertical speed), and round-out (UK) / flare (US) with idle engine(s). This is achieved with a beacon that has a heart-shaped horizontal radiation pattern (heart-tip at the antenna system), angled towards the inbound approach direction (line hearth-tip / heart-dip crossing the approach track outside the airfield perimeter). Radiation pattern obtained with 2 vertical antennas, spaced 3.87λ or 1.95λ, fed 180° out of phase. Also see Kramar/Hahnemann's equivalent 1938 US patent 2241907, and Kramar's 1939 German 1-course expansion patent 2241915]
2212238 US 1938 Frederick A. Kolster Int'l Telephone Development Co. (part of Int'l Telephone & Telegraph Corp. (ITT), the parent company of C. Lorenz A.G. since 1930) --- "Ultra short wave course beacon" [100% copy of the Lorenz A/N with dipole & switched reflectors landing beam system, with operating frequency increased to higher VHF [30-150 MHz, vs. 30 MHz for standard Lorenz A/N system], so as to avoid night-effect / ionospheric distortions (but susceptible to reflections from terrain and man-made structures), with an added colocated beacon with figure-of-8 pattern for wide-angle approximate location by aircraft far from primary course lines]
2282030 US 1938 Henri Busignies Henri Busignies --- "System of Guiding Vehicles" [Ground-based D/F apparatus comprising 2 sets of 3 antennas (1x 3 orthogonal loops, 1x 3 orthogonal crossing dipoles), eliminating night effect and aircraft effect (transmitting with trailing antenna = horizontally polarized); 2 antennas of each set are connected via amplifiers to 2 pairs of oscilloscope deflection plates. The remaining antennas are alternately connected to a signal strength indicator via an amplifier.]
2290974 US 1938 Ernst Kramar C.Lorenz A.G. --- "Direction Finding System" [Method of indicating equisignal beam beacon (2 switched directional antennas or 1 omni antenna + 2 switched reflectors) course line deviation, by comparing amplitude of the 2 signals. Standard Visual Indicator (vibrating reeed) for use with non-keyed 2-tone equibeams does not provide acoustic deviation indication, but pilot requires both to be available simultaneously. Existing instruments for equisignal beam aural beacons are based on electrical pulses derived from the flanks of the received tone pulses (rectified tone-pulses ( = DC-pulses) are passed through a transformer ( = inductance), which creates a positive induction pulse for each rising flank of a DC pulse and a negative pulse for each falling flank, the pulse amplitude being proportional to the DC-pulse amplitude ( = relative tone strength). This only works with beam-keying with single elements per side (e.g., complementary E/T keying, with only dots on one side, only dashes on the other). However, with these, it is difficult to assess the course deviation by listening to the combined audio signals (except for very large course deviations, when only one sub-beam is received). Aural interpretation is better with complementary dots & dashes keying patterns where both characters have the same number of dots and the same number of dashes (A/N, D/U, etc.). However, these cannot be used with the existing "kicking meter" indicators. Patent fixes this limitation, by inserting a 2-tone filter + 2nd rectifier stage between the 1st rectifiers and the standard summing moving-coil meter. Filters tuned to the repetition rates of the positive (or negative) induction pulses (i.e., factor 2:1). Hence, meter decaying pulse reflections to one side for "A" and to the other side for "N". This is a co-patent / split-off of Kramar's 1939 US patent 2241915. Also see Kramar's 1931 US patent 1949256, and L.M.T. Co.'s 1937 French patent 816120, p. 99 in ref. 21B.]
2297228 US 1938 Ernst Kramar C.Lorenz A.G. --- "Glide Path Producing Means" [Equivalent to Kramar's 1937 German patent 720890]
2288196 US 1938 Ernst Kramar C.Lorenz A.G. --- "Radio Beacon System" [Equivalent to Kramar's 1938 German patent 731237, with some expansion.]
7105791 RP 1938 Ernst Kramar & Heinrich Nass C.Lorenz A.G. "Sendeanordnung zur Erzeugung von Leitlinien" "Arrangement for producing course guide-beams" [The standard "Lorenz Beam" equisignal beacon configuration ( = 1 vertical dipole + 2 reflectors, per Kramar/Lorenz 1932 German patent 577350) is based on complementary keying of the reflectors, and transmitting continuous single tone via the dipole. Equisignal "visual" beacons continuously transmit 2 overlapping sub-beams with different tones, which allows simpler indicator system. Patent modifies the "Lorenz beam" configuration, by not hard-keying the reflectors, but replacing their keying switches / relays with interruptors / variable capacitors / goniometers that are each driven by seperate motor; one motor with 90 rpm, the other with 150 rpm, resulting in 90 & 150 Hz modulation respectively ( = standard modulation tones of Visual Equisignal Beacons), and constant carrier transmitted via the dipole. However, without further measures, this this results in suppression of the equisignal course-lines! This is fixed by changing the reflector length and reflector-dipole spacing such that the deformed dipole patterns have less overlap. Same result if, instead of dipole & reflectors placed on a straight line, they are arranged as a triangle. Can be used with standard Visual Indicator (e.g., reeds). Also see Kramar/Nass's equivalent 1939 US patent 2238270]
2241907 US 1938 Ernst Kramar & Walter Max Hahnemann C.Lorenz A.G. --- "Landing Method and System for Aircraft" [Equivalent of Kramar's 1932 German patent 711673]
2238270 US 1939 Ernst Kramar & Heinrich Nass C.Lorenz A.G. --- "Radio Direction Finding System" [Equivalent of Kramar's 1938 German patent 710591]
2210664 US 1939 Ernst Kramar & Walter Max Hahnemann C.Lorenz A.G. --- "Radio Direction Finding System" [Equivalent to Hahnemann/Kramar's 1937 German patent 734130 (UHF beacon with horizontal diople just below ground level at the intended touch-down point (FD: i.e., per Diamond/Dunmore's 1933 US patent 2120241).]
525359 GB 1939 Frank Gregg Kear Frank Gregg Kear --- "Improvements in or relating to radio transmitting systems" [Equisignal beam beacon, with antenna configuration comprising 2 omni-directional antennas, spaced ½λ and alternately & complementary keyed in-phase and 180° out of phase, to create 2 overlapping cardioid patterns. Alternatively: 2 separately fed omni-antennas, physically spaced ¼λ, with bi-directional transformer-coupled ¼λ feedline between them (= 90° phase difference); can be generalized for X° physical spacing; antennas fed by transmitter(s) via transformers, either 2 tones (Visual Range) or complementary keyed Aural Range. With this arrangement and resulting sub-beam patterns, contrary to conventional 2-/4-course beacons, there is no need for TO/FROM switching on the indicator, as the same characteristic signal (keying pattern or tone) is always (i.e., for all 4 courses!) on the same side of the equisignal beams when flying FROM (or, conversely, TO) the beacon! Various transmitter / modulator-amplifier / transformer configurations.]
2255741 US 1939 Ernst Kramar C.Lorenz A.G. --- "System for determining navigatory direction" [Equivalent to Kramar's 1938 German patent 731237]
718022 RP 1939 Ernst Kramar C.Lorenz A.G. "Antennenanordnung zur Erzeugung einer Strahlung für die Durchführung von Flugzeugblinlandungen" "Antenna configuration for generating a beam for blind landing of airplanes" [Expansion of Kramar's 1938 German patent 711673]
2241915 US 1939 Ernst Kramar C.Lorenz A.G. --- "Direction-Finding System" [Expansion of Kramar's 1938 German patent 711673. Instead of a 2-course glide path beacon with 2 antennas spaced 3.87λ or 1.95λ and fed 180° out-of-phase, now a 1-course beacon based on same cardioid pattern concept, with 2 linear arrays with 3.87λ or 1.95λ spacing between array centers, each array comprising 4 antennas with ¼λ spacing, and the 2 arrays fed 180° out of phase.]
2272997 US 1939 Andrew Alford Int'l Telephone Development Co. (part of Int'l Telephone & Telegraph Corp. (ITT), the parent company of C. Lorenz A.G. since 1930) --- "Landing beacon system"  [2-transmitter beacon system, one producing landing beam with curved, constant field intensity approach path, the other (also) located on the approach course but displaced in the direction of the approach, its field combining with the first, so as to create a linear (straight) landing path.]
767254 RP 1939 Ernst Kramar C.Lorenz A.G. "Verfahren zur kontinuierlichen Ortsbestimmung eines Flugzeuges längs der Anflugstrecke zu einem Landeplatz" "Method for continuously determining position of an aircraft along a the approach path to an arfield"  [From marker beacon to touchdown, rotating wave interference pattern, one beam with phase modulation, one with unmodulated CW, wavelength at least approach path length, e.g., 900 m or 4 km, located at departure end of runway]
2294882 US 1940 Andrew Alford International Telephone & Radio Mfg. Corp. [subsidiary of ITT] --- "Aircraft Landing System" [methods & means for providing a glide path with antenna location remote from landing runway [FD: beside runway, abeam T/D point]; parabolic/curved GP too steep at higher alt, but correct shap at T/D point; straight GP at higher altitude but too sharp angle at T/D point; patent proposes hyperbolic GP shape that is substantially straight but curved at lower alt; antenna system has symmetrical pattern in opposite directions, i.e., 2 GP's in opposite directions (FD: undesirable, since only 1 can serve a correct T/D point!)
2404501 US 1940 Frank Gregg Kear Frank Gregg Kear --- "Radio beacon system" [VHF rotating-beam radio beacon with, e.g., 200-300 MHz carrier frequency; narrow beam rotates in azimuth at a constant rate (e.g., 12-30 rpm); the 360° azimuth is divided into a fixed number of consecutive arc-segments (e.g., 5° wide), starting with, e.g., north. The odd-numbered segments all have a different-but-fixed modulation tone. No transmission when beam sweeps through an even-numbered segment. E.g., with 5° wide arc-segments, 36 segments each with a distinct tone, interspersed with 36 no-tone segments. A receiver on an abritrary azimuth/course, will receive sequentially 3 tones: the strongest is the tone associated with the arc-segment in which that course lies; this is preceded by the (weaker) tone of the preceding arc-segment and followed by the (weaker) tone of the next arc-segment. Transmitter has tone-modulator with tone stepwise altered by same motor as rotating the directional antenna. Receiver has 3 audio filters with center frequency that is operator-selectable to the tone-combination of the desired & adjacent arc-segments. The tone of the center arc-segment directly drives a signal strength indicator. The other 2 tone filters are both followed by a slow-decay signal peak-capturing circuit, the outputs of which drive a zero-center meter, indicating relative strength (with sign) of the 2 adjacent arc-segment signals. Instrument provides continuous indication of deviation from any selectable course.]
2283677 US 1940 Armig G. Kandoian Int'l Telephone & Radio Mfg. Corp. --- "Localizer beacon" [ILS localizer system, 5 loop antennas, transmission line bridge, 2-tone continuous modulation]. Also see 1951 "Localizer antenna system" US patent 2682050 by A. Alford.
2288815 US 1940 David G.C. Luck Radio Corporation of America (RCA) --- "Omnidirectional radio range" [equivalent to the German UKW-Phasendrehfunkfeuer “Erich”; precursor to the post-WW2 VOR system]
581602 GB 1942 Robert James Dippy Robert James Dippy --- "Improvements in or relating to Wireles Signalling Systems" [invention of the Grid / GEE/ G hyperbolic system; covers GEE pulse-signals receiver & CRT display system design]
581603 GB 1942 Robert James Dippy Robert James Dippy --- "Improvements in or relating to Wireles Systems for navigation" [co-patent to Dippy's 1942 British patent 581602]
2436843 US 1943 Chester B. Watts & Leon Himmel Federal Telephone & Radio Corp. [subsidiary of ITT] --- "Radio Antenna" [UHF directional antenna system with 2 overlapping beams, radiating predominantly horizontally polarized waves, without rear lobes, suitable for operation with a mobile glide path transmitter, lower end of GP changes from straight GP angle to zero; finalization of US patent 2419552 (filed 1 month earlier) with same title, by Leon Himmel & Morton Fuchs]
862787 DP 1944 Joachim Goldmann C.Lorenz A.G. "Antennenanordnung zur Erzeugung von ebenen Strahlungsflächen der Strahlung Null" "Antenna configuration for generating narrow nulls in beam radiation pattern" [Invention of the "Elektra" multiple beam system]
148430 GB 1918 Hugo Lichte Hugo Lichte --- "Improvement in navigation by means of an alternating current cable located in the water" [inductive pilot-cable / leader-cable; also same-date French patent 524960]
163741 GB 1919 William Arthur Loth William Arthur Loth --- "Improvements in the system and apparatus for enabling a movable object to pursue an electrically staked out route in a more precise way than by means of visual points of reference" [inductive pilot-cable / leader-cable system for surface/submerged ships/boats, energized with electrical power with specific rhythms or frequencies.]
423014 DE 1919 William Arthur Loth William Arthur Loth "Empfangseinrichtung auf Fahrzeugen zur Navigation nach Führungskabeln" "Reception arrangement on vehicles for navigation by pilot-cables / leader-cables" [crossing loop antennas and "Telefunken Compass" switched dipoles in star-configuration]
410396 DE 1920 William Arthur Loth William Arthur Loth "Vorrichtung zur Navigierung von Fahrzeugenm insbesondere von Schiffen" "System for navigation of vehicles, in particular of ships" [crossed-loops receiver antenna for inductive pilot-cable / leader-cable system]
2224863 US 1938 Edward N. Dingley Edward N. Dingley --- "Blind landing equipment" [inductive pilot-cable / leader-cable system, cables in or on ground; with equi-signal; supplemented by 1938 US patent 2340282 and its equivalent 1938 GB patent 522345 ]
820319 GB 1950 Brian D.W. White National Research Development Corp. --- "Improvements in or relating to azimuth guidance systems" [aircraft azimuth guidance system; a wire supplied with AC power runs parallel with each side of the runway; the frequency of the supplies are either different or have the same carrier frequency with differing modulation frequencies and two equisignal fields exist along the runway center line; aircraft equipped with pick-up loop(s) to detect EM field and derive position relative to the wire(s) and runway center line.]

Table 3: Selected patents regarding radio direction finding, radio location, radio navigation through WW2


Note 1: due to copyright reasons, this file is in a password-protected directory. Contact me if you need access for research or personal study purposes.

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