Luftwaffe radio equipment (Funkgerät) of World War II
During World War II, the German Luftwaffe relied on an increasingly diverse array of communications, IFF and RDF equipment for use in its aircraft and on the ground. Most of this equipment received the generic prefix FuG for Funkgerät, meaning "radio equipment". Most of the aircraft-mounted Radar equipment also used the FuG prefix. This article is a list and a description of the radio, IFF and RDF equipment.
FuG I: An early receiver/transmitter set manufactured by Lorenz. It operated in the 600 to 1667 kHz range (generally the entire American AM radio broadcast band) at a power of 20 to 100 watts, depending on installation.
FuG II: An update of the FuG 1, also manufactured by Lorenz, that operated in the 310 to 600 kHz frequency range.
FuG 03: Codenamed Stuttgart, was an airborne receiver/transmitter set used in bombers. Was fitted in: Do 11, Do 17 E and F, Fw 58, He 114, Ju 52, Ar 66, Ar 96, Junkers W 33 and W 34. Set consists of: S 3a Transmitter; E 2a Receiver. Power source: G 3 Air-driven generator and 2 - 90 volt dry cells. The FuG 03 operated in the 1250 to 1400 kHz frequency range.
FuG 7: A compact airborne receiver/transmitter used in fighters and dive bombers. Prior to 1943, it was fitted in the Bf 109C to G-2, and Fw 190 A-0 to A-3. After 1943, it was still fitted in the Ju 87 and Hs 129. The FuG 7 typically operated in the 2.5 to 7.5 MHz, with a power of approximately 7 watts. The range of the FuG 7 was approximately 50 km in good weather. Later versions of the FuG 7 included the FuG 7a, which included the S 6a Transmitter, E 5a Receiver and Junction Box VK 5 A.
FuG 10 series: A family of transceivers for both R/T and W/T communications. The German FUG-10 panel, or rack, contained two transmitters and two receivers: One transmitter and its companion receiver operated in the MF or Longwave; 300 to 600 kHz (1,000 to 500 m) range and the other transmitter and its companion receiver operated in the HF or Shortwave range; 3 to 6 MHz (100 to 50 m). Most of the FuG 10 series used a fixed wire aerial between the fuselage and tailfin or a retractable trailing aerial wire. The FuG 10P replaced the standard E 10L longwave receiver with an EZ6 unit for a G6 direction finding set. The FuG 10ZY incorporated a fixed loop D/F aerial and a homing device for navigation to a ground station. This loop aerial, usually fitted on a small, "teardrop" shaped mounting, was standard equipment on most fighter aircraft from late 1943 on. Manufactured by Lorenz. Typical power was 70 watts.
FuG 11: Developed as a replacement for the Fug 10 series. No MF mode being HF only (3Kw) . Increased frequency range to 3 - 30 MHz. CW & AM voice. Reduced volume, cost & weight. Intended to be combined with the PeilG 6 & FuBL 2. It could be fitted with a remote control system that allowed the pilot to control it rather than the radio operator. Development completed but never deployed as there was little demand for long range bomber communications in 1944.
FuG 13: Designed to supplement early versions of the Fug 10 to improve long range communications. Frequency range 3Mhz to 20 MHz 20 Watts. Deployed on long range aircraft such as the Fw 200 Condor. Improvements in the Fug 10 family resulted in no need for this additional radio and it was withdrawn from service.
FuG 15 : Intended as the next standard aircraft transceiver to replace earlier series units. Unusual in using FM as well as AM for voice. Operating Frequency 37.8 to 47.7 MHz. It could be fitted with a remote control system that allowed the pilot to control it rather than the radio operator. Production planned to start in 1942 but service trails showed problems and deployment stopped. Replaced by the Fug16. Completed units rebuilt at BS 15 navigation radio beacons in 1945.
FuG 16 Z, ZE and ZY: These sets were airborne VHF transceivers used in single-seat fighter aircraft for R/T and W/T communications, and were also used for ground fixes and DF homing on ground stations when used in conjunction with the FuG 10P or FuG 10ZY. Installed for Bf 109G-3/G-4 and later, FW 190A-4 and later subtypes. Frequency Range was 38.5 to 42.3 MHz. The FuG 16ZY was also used for Y-Verfahren (Y-Control), in which aircraft were fitted up as Leitjäger or Fighter Formation Leaders that could be tracked and directed from the ground via special R/T equipment. Aircraft equipped with ZY were fitted with a Morane whip aerial array. Principal components: Transmitter, Receiver, Modulator in one case, S 16 Z Tx, E 16 Z Rcvr, NG 16 Z Modulator Dynamotor U 17 Antenna Matching unit AAG 16 Z Modulator Unit MZ 16 Homing Unit ZVG 16 Indicator AFN - 2
FuG 17 Z and ZY: These sets were airborne VHF transceivers used in Close Air Support aircraft for R/T and W/T communications with ground units. Frequency Range was 42 to 48.3 MHz. This matched the ground forces Fug 7 radio fitted to command tanks and reconnaissance units. The FuG 17 was identical to the Fug 16 with the exception of the frequency range and seems to have been deployed first. In the Fug 17ZY version it was also used for Y-Verfahren (Y-Control), though it seems to have superseded it this role by the FuG 16ZY when it became available.
FuG 18: Developed in 1944 as an improvement to the Fug 15. Frequency range 24 - 75 MHz. FM & AM voice. FuG18Y included the ability for Y-control, blind landing and Hermione beacon receive.
FuG 24: This set was developed from the Fug 16 as a simplified and cost reduced system. Intended for the Heinkel He 162 and later aircraft. Did not have a direction finder capability or a Y control interface. Frequency Range was 42 to 48.3 MHz, FM & AM voice only. FuG 24Z included Y-Control and blind landing and Hermine beacon-receiving capability.
Peilgerät (PeilG) 6: Codenamed "Alex Sniatkowski", this was a long and medium range D/F set and homing device used mainly on bombers: Ar 234, Do 217, Ju 87, Ju 88A-4 on, Ju 188, Ju 290, Ju 388; the He 177 heavy bombers (Germany's only "heavy bomber" design in service), and both the He 219A and Ju 88G night fighter series are some of the aircraft types to be fitted. Frequency range was 150 to 1,200 kHz. A "flat" equivalent of a D/F loop was used for the Peilgerät device to reduce drag over a protruding D/F loop antenna, and made up of a series of metal strips in a "sunburst" pattern. often being fitted under a round, flush fitting plexiglass cover. A small "whip" aerial was also fitted to the FuG 10 radiomast. Manufactured by Telefunken. Version PeilG 5 was of similar performance but used a manually controlled loop antenna. Control was via an electric servo motor. Versions 1 - 4 had manual control either via cable linkage or direct control via an attached handle.
FuBL 2 Used the Knickebein beam navigation and bombing system. Consisted of the EBL 3 and EBL 2 receivers with display device ANF 2. The EBL 3 operated between 30 and 33 MHz and received 34 channels, The EBL 2 operated at 38 MHz and was unchanged from the FuBL 1 system. The AFN 2 provided the pilot with a left/right display and a signal strength. The unit was available in two versions FuBL 2 H for a unit operated by the radio operator and the FuBL 2 F for remote operation by the pilot in a single seat aircraft.`The primary difference between the EBL 1 and the EBL 3 was sensitivity to allow, what was basically a ILS system, to be used for bombing.
FuG 28a: Y-Gerät transponder. Based on the Fug17 transceiver with additional components to send the response to the Y-Gerät ground station for the ground station to derive range. Also derived the azimuth signal and displayed the results on the ANF 2 display giving the pilot a left/right command. Operating frequency 24 - 28 MHz. 8 Watts transmit power. The unit also interfaced to the FuG 10 system in the aircraft so that voice communication with the pilot from the ground controllers via the Fug 28a was possible.
Hermine: This system was a VHF radio beacon. Originally developed in 1942 due to problems the design was suspended. When in 1944 the existing radio navigation systems were either being jammed or under physical attach the design was revisited. It consisted of a rotating radio beacon transmitting at 30 -33 MHz. The signal consisted of a tone and a robot voice using AM. The robot voice was encoded onto an optical disk. The voice spoke a number between 1 and 35, corresponding to 10 degrees of angle from the beacon. The pilot listened to the signal, when the tone disappeared the next number corresponded to the angle from the beacon. It was expected that this would give an angular resolution of about 5 degrees but when tested it was found that some pilots could estimate to within 3 degrees. The receiver was a modified EBL 3 which had had its bandwidth increased and fed the audio signal via the Fug16 to the pilot. In single-seater aircraft the radio fit was numbered FuG 125. The beacon identifier was transmitted instead of the number 0. This allowed a pilot to select a particular beacon. Between 10 -20 beacons were commissioned by May 1945. 30 channels were available with 2 more being reserved for airfield ILS. Beacons were usually placed 20 km from a runway, The pilot would over fly the beacon and then circle until he acquired the ILS landing beam on the FuBL 2 equipment.
FuG120/FuG120k Bernhard: The "Bernhard/Bernhardine" system was a nightfighter/day fighter radio-navigation system. Primary intended to guide fighters into the bomber streams rather than against individual aircraft. The ground station (FuSAn 724/725) "Bernhard" was the VHF rotating directional-beacon ground-station. It continuously transmitted the station identifier and the antenna azimuth (bearing) in Hellschreiber-format. The FuG 120 "Bernhardine" was the airborne Hellschreiber system that prints the data stream from the selected Bernhard station. The HF receiver for the system was the EBL3 from the FuBL 2 ILS system. Operating Frequency: 30 - 33.1 MHz, Transmitter power: 2 × 500 Watt (FuSAn 724) or 2 x 5000 Watt (FuSAn 725). Antenna rotational speed: 12 degrees per second (2 revolutions per minute). Accuracy: initially ±1°, then improved to ±0.5°. The system was initially deployed in 1941/42 however work was stopped until 1944. Deployment was started to try and produce a "jam proof" system. A later version (deployed at about 3 sites) alternated between sending angular information and text message instructions which allowed a simple form of data link between the fighter direction stations and the fighters. FuG 120k: This version was developed as the original unit was bulky and expensive. In return for considerable reduction is size and weight azimuth measurement was reduced to approx. 4 degrees.
Instrument Landing Systems
FuBL 1 Used the Lorenz landing beam system. Consisted of the EBL 1 and EBL 2 receivers with display device ANF 2. The EBL 1 operated between 30 and 33 MHz and received the azimuth signals from a transmitter at the far end of the runway, The EBL 2 operated at 38 MHz and received the two marker beacons as the aircraft approached the threshold to land. The AFN 2 provided the pilot with a left/right display and a signal strength. The pilot could also hear the azimuth signal and the marker beacons in his headset. When the aircraft passed over the beacons a light was also illuminated in the cockpit.` 
FuG 125 Hermine: Was a system designed for night fighters and single pilot aircraft in night/poor visibility conditions. It consisted of several sub systems. For navigation it used the "Hermine" VHF radio beacon signal system via the Fug 16ZY. For approach and landing it used the FuBL 1 or 2 blind landing receiver. For altitude it used the Fug 101 radio altimeter. Given the pilot workload in a single pilot aircraft it also included a simple auto pilot. Fitted in some types of Fw 190 and Bf 109s. Manufactured in small numbers by Lorenz in 1945. 
FuG 101: FM (Frequency Modulated) CW (Continuous Wave) Altimeter. Operating frequency 337 - 400 MHz. (75 – 89 cm) Selectable between two ranges, 0 - 150 Meters and 0 - 750 Meters. Units were small enough to be fitted to single-engine day fighters and night fighters. Fitted generally at first but later in the war only to aircraft expected to operate at night. In larger aircraft usually paired with Fug 102 due to its max height limitation.
FuG 102: Pulse modulated Altimeter. Operating frequency 182 MHz. Usable between 100 Meters and 15,000 Meters. Due to its limited minimum height usually paired with Fug 101. Too large to fit in single-engined fighters.
FuG 103: Pulse Modulated Altimeter. Improved version of Fug 102 with reduced min height limitation, therefore Fug 101 could be dispensed with. Small numbers produced in 1945.
FuG 104: Improved Fug 103 by reducing its size. Development never completed.
Flak Fire Control
FuG 25z Zwilling : This was an early IFF set designed to respond to the Würzburg. The reception frequency range was 600 MHz 50 cm. Transmitting frequency was also 600Mhz, 50 cm. When it responded the radar operator could hear a morse character in their headphones. This only worked with the Würzburg radars not Freya. It could be received at up to 30 km (19 mi).
FuG 25z Häuptling As experience was gained it was discovered that using the system above the radar operators were unable to identify which aircraft had responded to the interrogation pulse as the basic system did not provide range. In an attempt to resolve this question a modification was applied turning the Zwilling into the Häuptling.This retransmitted the receiving pulse on the 160Mhz frequency to a receiver on the radar. However, by the time that this modification had been developed jamming of the Würzburg had commenced and the radar had been modified to work on one of three bands called "islands". As the Häuptling could not cover these bands it was abandoned and the FuG 25z was replaced by the various versions of the FuG 25a system.
Originally IFF was only considered to be of use with Flak hence the limitation above. As the war progressed it was realised that IFF should also work with early warning radars hence a new version of the FuG 25 was developed.
Early Warning Radar
FuG 25a Erstling: This was an IFF set designed to respond to Freya, Würzburg and the advanced, limited-deployment FuG 404 Jagdschloss system. The reception frequency range was 125 + or - 1.8 MHz. Transmitting frequency was 160 MHz. It could be received at up to 100 km (62 mi).
Würzburg radars as they worked on a different band required separate equipment to work with the FuG 25a. This was known under the name Kuckuck. It consisted of the interrogator transmitter Kur and the receiver Gemse. Dipoles were mounted inside the reflector to transmit and receive. A severe problem was encountered with the width of the resulting beam.
FuG 225 Wobbelbiene This was a development of the FuG 25z to provide a wide band receiver which would respond to the Würzburg "Island A" & "Island B" frequencies. It was hoped by doing this that the beam width problems with Fug25a would be resolved. However, by the time this was ready for production in 1944 Flak Würzburg now included "Island C' which could not be received. The unit was therefore never deployed. Further development of the basic Fug 25 was then abandoned.
FuG 25a Erstling-Rot: With the introduction of PPI radars such as Jagdschloss a problem was encountered with the FuG 25a in that the dwell time of the radar was too short for the operator of the system to observe, in many cases, the mark on their screen. Earlier radars which "stared" rather than scanned did not have this problem. This modification increased the duration of the response signal so that this did not happen.
FuG 25a Erstling-Grün: In anticipation of the allies jamming of the 125/160 MHz IFF frequency this modification changed the interrogation wavelength to 2.5 meters and the response to 2 meters. No other changes were made. Never deployed.
FuG 226 Neuling: Intended to incorporate all the lessons using the preceding systems. The objectives of the design were ; (a) Work with all anticipated service radars i.e. "staring and PPI' (b) operate at 6, later 12 frequency pairs to defeat jamming (c) for the first time provide an air-to-air mode. Development never completed.
Frischling: With the deployment starting on 9 cm band radars such as the Jagdschloss Z, a need for IFF was identified. The Frischling was an add on unit for either FuG 25a or FuG 226 that converted the 9 cm integration pulse to a standard 125 MHz pulse which was then passed it to the response unit. It does not seem to have been issued a Funkgerät designation number. Development not completed.
Ground-to-Air Data Links
As allied jamming of the fighter voice links became increasingly effective by 1944/45 attempts were made to find other ways of passing information and commands to fighter pilots.
Nachtlicht: The receiver for this was the FuG25a IFF system. When a ground station interrogated the unit it flashed a small light to indicate this had happened to the pilot. The system involved modifying the transmitter so that the light flashed Morse signals. This allowed a very primitive way of signaling the pilot. A development of this system was to include a unit called the Luftkurier which decoded the Morse and indicated commands on a pointer (left/right). The system was trialed but it was found to be too hard for pilots to watch the indicator while piloting their aircraft. Another issue was that the Luftkurier was found to be very easy to jam.
Fug 136 Nachtfee: A development of the Nachlicht system. Used the Fug25a receiver again. This time commands were decoded onto a small CRT, which allowed up to 16 commands to be issued to the fighter. Had the same problems as Nachlicht, too easy to jam and too hard to use in a single-seater plane. Abandoned.
Fug 138 Barbara: A further development of the Nachlicht system. This time an audio receiver was added to the system between the Fug25a and the Fug16ZY. This allowed the pilot to hear Morse commands sent up the data link. Unusable in practice and abandoned.
As German pilot training was cut back due to the war situation it was realised that the above systems would be unusable as pilots were no longer being trained in Morse. This led to the The Fug 120 and Fug 136 systems.
FuG 139 Barbarossa: This system again used the Fug25a receiver but fed it to a Hellschreiber printer. This removed the requirement to read Morse or continuously watch a display. Deployed in small numbers in 1945. An attempt was being made to use Pulse Modulation to also transmit voice but this was never completed.
NS 2 : Single watertight box transmitter. Operated on the international distress frequency of 500 kHz. Powered by a hand generator. Sent Morse code, no receiver. Fitted to most German aircraft expected to operate over water at the start of the way. Range 120 – 250 miles. Transmit power 8 Watts.
NS 4 : Single watertight box transmitter. Operated on a frequency of 53.5 to 61 MHz. Powered by a batteries. Sent Morse code, no receiver. Fitted to most German aircraft expected to operate over water from the middle of the war. Replaced NS2. Range 6 to 16 Miles. Easier to use than the NS2. Transmit power 1 to 2 watts.
FuG 141: Receiver for signals from the NS4 emergency transmitter. Fitted to air-sea recsue units. Operated with a direction finding loop.
FuG 142: Receiver to receive MW beacons. Battery powered to be used when other power had failed on an aircraft. Not deployed after service tests had revealed problems. Due to be replaced by the FuG 145
Fug 145: Replacement for the PeiGL 6 MF receiver. Development not completed.
The Luftwaffe was known to have fitted small aluminum strips which frequently carried explosive charges onto the outside of the equipment aluminium housings. These explosives were linked then by a fuse (a slow match cord that when ignited, allowed for the evacuation of the crew) onto any sensitive apparatus, which allowed it to be destroyed rather than be captured by the Allies.
- Aders, Gebhard. History of the German Night Fighter Force 1917-1945. London: Jane's Publishing Group Limited, 1979. ISBN 0-354-01247-9