German Luftwaffe and Kriegsmarine Radar Equipment during World War II, relied on an increasingly diverse array of communications, IFF and RDF equipment for its function. Most of this equipment received the generic prefix FuG (), meaning "radio equipment". During the war, Germany renumbered their radars. From using the year of introduction as their number, they moved to a different numbering scheme.

Searchlight and fighter control

No German ground radar was accurate enough for flak fire direction. The method of operation during the day was for radar to direct the flak's optical fire control towards the target. Once this was acquired, the flak was controlled by the optical equipment to complete the engagement. During the night, the radar would be used to indicate the target to the searchlight crews. The rest of the engagement would be carried out optically. During the day, fighters would be directed with sufficient precision for them to come into visual contact with their targets, while during the night they would use their onboard aircraft interception (AI) radar to find the target after initial direction from the ground-based radars.

Early Units

Device Name Code Name Device Description FuMG 38L Kurfürst Two 2.4-meter parabolic reflectors (one transmit and receive) mounted on a converted Flak mounting. Wavelength 62 cm; range approx 8–12 km. FuMG 39L Kurpfalz A more powerful development of the 38 L. (the L in the designation meant it was built by Lorenz.). Dished units were mounted on the operations van. FuMG 40L Kurmark Developed version of the 39 L; range now up to 25–40 km.

Würzburg

The Würzburg was first operational in the summer of 1940, had a parabolic shaped antenna with a diameter of about 3metres and in some models could be folded in half for transport. The Würzburg was produced in the thousands with various estimated figures being between 3000 and 4000 with up to 1500 sets of Würzburg Riese. The antenna of the Würzburg weighed over 9.5 tons and its parabolic surface had a diameter equal to 7.5 metres and a focal length of one metres and 70 cm. Only one German company had the technical skill to build these radars, and that was Zeppelin. The name of the unit was chosen at random by pointing at a map of Germany and Würzburg was chosen.

FuMG 62 / FuMG 39 Würzburg: 3D fire-control radar. Used to direct the flak optical directors and searchlights. Wavelength 50 cm approx. In response to jamming various models of Würzburg radar were developed to operate on various frequencies called "Islands".

Würzburg A First production version introduced in 1940. 50 cm operating wavelength. Operation range was approximately 30 km. Included an IFF system that worked with the FuG 25z airborne unit.

Würzburg B Integrated IR telescope to increase accuracy. Proved unsatisfactory and not placed into production.

Würzburg C Replaced the model A in production in 1941. Had lobe switching to improve accuracy. On this unit the integral IFF system was replaced by a system based on the FuG 25a airborne. To support this system which worked at approx 125-160 MHz two antenna were placed inside the main dish. A separate interrogation and receiving units were attached to show the IFF responses.

Würzburg D Replaced the model C in production in 1942. It now had a usable range of approximately 40 km. Conical scan was used for fine accuracy. The IFF antenna was now fitted in the center of the dish rather than on the sides. Better instruments were fitted and generally, it was the best of the small Würzburg.

FuMG 65 Würzburg Riese (Giant): The electronics of the D model Würzburg combined with a 7-meter dish to improve resolution and range. Range approx 70 km. Version E was a modified unit to fit on railroad flatcars to produce a mobile Flak radar system. Version G had the 2.4-meter antenna and electronics from a Freya installed. The antenna dipoles were inside the reflector. The reason for this was that the allies were flying very high recon flights which were above the maximum height of the Freya. The standard Würzburg Riese's 50 cm beam was too narrow to find them directly. By combining the two systems the Freya could set the Würzburg Riese onto the target.The Radar War: Germany's Pioneering Achievement 1904-45

Mannheim

FuMG 63 Mainz The Mainz, introduced in 1941, was a development from the Wurzburg with its 3-meter solid metal reflector mounted on top of the same type of control car as used by the ‘Kurmark’. Its range was 25–35 km with an accuracy of ±10–20 meters, azimuth 0.1 degrees, and elevation ±0.3-0.5 degrees. Only 51 units were produced before being superseded by the ‘Mannheim’.

FuMG 64 Mannheim The Mannheim was an advanced development from the ‘Mainz’. It also had a 3-meter reflector, which was now made from a lattice framework covered in a fine mesh. This was fixed to the front of a control cabin and the whole apparatus was rotated electrically. Its range was 25–35 km, with an accuracy of ±10–15 meters; azimuth and elevation accuracy of ±0.15 degrees. Though accurate enough to control Flak guns it was not deployed in large numbers. This was due to its cost (time and materials to manufacture was about three times that of a Würzburg D).

FuMG 75 Mannheim Riese Just as the Wurzburg's performance was greatly improved when fitted with a 7-meter reflector, so was the Mannheim's, and the result called a Mannheim Riese (Giant Mannheim). There was an optical device for the initial visual acquisition of the target. With its narrow beam it was relatively immune from ‘Window’. Its accuracy and automatic tracking enabled it to be used in anti-aircraft missile research to track and control the missiles in flight. Only a handful were manufactured.

FuMG 68 Ansbach There was a need for a mobile radar with the range and accuracy of the ‘Mannheim’. The result, in 1944, was the Ansbach. It had a collapsible reflector of diameter 4.5 meters, operating on a wavelength of 53.6 cm, and peak power of 8 kW, giving it a normal range 25–35 km (70 km in search mode) with an accuracy of 30–40 meters. Azimuth and elevation accuracy was around ±0.2°. The antenna and reflector were remote controlled from a Bayern control van up to 30 meters away. The control system was based on the remote control system of the Michael microwave communication system, this was based on the Ward-Leonard AC/DC control system. The Ansbach was to be installed in large Flak batteries with six or more guns, but only a few were produced by the end of the war, and these did not see operational service

Medium-range search

Freya & similar units

FuMG 450 Freya / FuMG 41G: This was a 2D Early warning radar. (2D means unable to indicate height). It was used for fighter direction and target indication for the Würzburg. Operating wavelength of approx 2.4 meters (125 MHz). In response to jamming various models were developed to operate on various frequencies called "Islands". Over 1000 units delivered in various models

FuMG 401 / FMG 42 FREYA - LZ (Models A - D). An Air portable version, the model differences were due to an operating frequency range being in 4 discrete bands between 91 and 200 MHz.

Freya-Rotschwarz and Freya-Grünschwarz: These two systems were Freya modified to operate on the same frequency as the British radio navigation system GEE to avoid jamming. However, as by the time they were ready the Germans were jamming GEE it is not clear whether any were ever deployed.

FuMG 451 A Freya Flamme: Freya which had been built to use the "Island D" band were modified to be able to trigger the British IFF equipment. Ranges of up to 450 km were obtained. Fell from use as British IFF procedures improved.

FuMG 401 Freya Fahrstuhl: A 3D version of the Fraya. (3D means could measure height). Measurements made by moving the antenna up and down on a rack. Only a very rough estimation of height available. originally intended for early warning most of the systems produced went to help "jammed" Würzburg

Freya EGON: EGON stood for Erstling Gemse Offensive Navigation system. Where Erstling was the codename of the Fug25a transceiver in the aircraft and Gemse was the codename for the receiver. The system operated on a principle similar to the British OBOE navigation system. An IFF signal was sent from a Freya, that had had its receiver antenna removed, to the aircraft. The Fug25a in the aircraft responded and the received signal was displayed as a range offset on the Freya display. Using a second transmitter and triangulation the position of the aircraft was resolved. Though the system was tested to guide night fighters it was found to be to limited by the number of aircraft that it could control at one time (the same limitation was found with Oboe). The "Y system" was used instead for night fighter control. The EGON system was used to control pathfinders for bombing raids over both England and Russia, however, by now the Luftwaffe bomber force was running out of planes, pilots and fuel so the results were minimal. Work was done using a third transmitter to improve system performance. Range with a normal Freya was up to 250 km, work was underway to use a Wasserman system instead of a Freya to increase range too 350 km. (the Freya signal was too weak to trigger the Fug25a at ranges beyond 250 km), but this was not completed.

Long-range search

For area air defense (vs point defense) Freya's range was found to be insufficient. This led to attempts to use Freya technology to achieve greater range. This resulted in the Wassermann and Mammut. Although the Mammut units achieved their aims they were large installations with large arrays built on bunkers. This resulted in long building times and vulnerability to air attacks. The Wassermann was a better solution in that being smaller they were harder to locate and quicker to build, 3–4 weeks. However, sources indicate that they never achieved the desired range of 400 km, the best was approx 300 km. This may be why there were so many variants deployed.

FuMG 401 Mammut: First deployed in 1942 this was a long range 2D search radar. It consisted of 8 Freya class antenna arranged in a 4 x 2 configuration. It measured 25 meters wide and ten meters high and was mounted on four pylons fixed in concrete. Some installations had a second array mounted back-to-back. Each array could be electronically swung through about 100 degrees, so the dual sided array could look behind itself to continue to track bombers as they flew into Germany. Frequency was the same as Freya (125 MHz). Range was up to 300 km with a transmit power of 200 kW. Installations being very large took up to four months to build.

FuMG 402 Wassermann: This system was deployed in 1942. It was basically six Freya antenna mounted on a rotation cylinder. Frequencies were similar to Freya (125 MHz) transmit power was 100 kW, resulting in a usable range of approx 200 km. Three main versions were produced with sub variants in each class.

Wassermann L: The original light version. Some sources indicate that it had structural problems.

Wassermann S: The heavy version. First deployed late 1942 Some sources indicate it had more than six arrays.

Wassermann M: The last family were the medium class units. Again, it is not clear exactly how many Freya arrays were attached to the mast. In 1944, this version received a modification that allowed it to electronically tilt its beams by 16 degrees which allowed it to perform height determination turning it into a 3D search radar.