radar (original) (raw)

Huelsmeyer had invented and demonstrated his radar in 1904. However, his invention was an idea too early for its time. On-the-other-hand, Prof. Dr. Hans E. Hollmann started his education and research at the right time and he worked with the right people. Modern radar was developed in Germany between the years of 1928 to 1940 and Prof. Dr. H. E. Hollmann was the leading expert in its development. Prof. Dr. H. E. Hollmann was a prolific inventor, a genius, and a specialist on microwave technology. Modern radar began with his work, his inventions, and his demonstrations and disclosure to the rest of the world of how it worked. As such, it is only appropriate to start with him when discussing the "birth of modern radar."

In 1927, while working for the Technical University in Darmstadt, Prof. Dr. Hans E. Hollmann developed and built the first ultra short wave transmitter and receiver for centimeter and decimeter waves. This work led to the development of the world's first microwave telecommunication system. In 1928 he graduated with a thesis on "Barkhausen" electron oscillations. At this time a scientist by the name of Hans-Karl von Willisen became good friends with Hollmann because he too was interested in ultra short waves. The two, with another man by the name of Guenther Erbsloeh, started a company called GEMA. Hollmann and von Willisen were the technical experts and Erbsloeh was the manager. GEMA built the first radar transmitter in the autumn of 1934 for detecting ships. The radar operated on 50 cm wave length and could find ships up to 10 km away. In the summer of 1935, a pulse radar was developed with which they could spot the ship the "Koenigsberg" 8 km away. This radar unit used the "Braunschen" tubes and had an accuracy of 50 m. A magnetron had been tried but the frequency was not stable, and as such, tubes were used. A wave length of 60 - 80 cm was used so the sender and receiver could be spaced close together. An airplane at a height of 500 m and a distance of 28 km could be seen. By 1935, they had built the first successful radar unit. For ship born application, they used the same radar system, except that the ship born system operated on a wave length of 80 cm instead of 1.8-2.0 m. The land based radar was called "Freya" and the sea born radar was called "Seetakt."

Based on Hollmann's work, a microwave department was set up at Telefunken in 1933. This company set about designing the "Darmstadt" radar (named after the university at which Hollmann studied for 9 years) in 1936. This radar was later named the "Wuerzbug." A parabolic antenna with a diameter of 3 m and a rotating dipole was used. The first unit had a range of 10 km with an distance accuracy of 100 m and an azimuth and elevation accuracy of 0.25 deg. The new radar was demonstrated to Commander Udet of the Air Force and he commented, "if you deploy this radar, its going take all the fun out of flying." By 1937, the range had been increase to 35 km. The Wuerzburg operated on a wave length of 53 cm.

During the war, the Freya and the Wuerzburg were paired so that the Freya would spot and track incoming aircraft and the Wuerzburg would determine the exact range and height when the aircraft came closer. The Wuerzburg-Riese was used to direct fighter aircraft against the incoming bombers.

These radars were far ahead of their time and they were very affective. By the end of the war 50,000 bombers had been shot down. However as the WWII continued, the Allies were working hard at catching up and it was not long before chaff or windows and other radar counter measures were developed and used to jam these radars. Counter measures such as changing frequencies were devised and so, the age of "electronic warfare" began.

Prof. Dr. Hans E. Hollmann continued working on radar in his company "Laboratory for High Frequency and Electromedicine" in Berlin. The company had a staff of 20 scientists and not only did they work for Telefunken but much of the research work went into helping GEMA. The Telefunken Co. owned many of Hollmann's radar patents which they registered in the US prior to the war. See patents. These patents were worth millions of dollars. Prior to WWII, the British and the US were not only aware of the radar technology being developed in Germany but they also used it to develop their radar systems.

	Prof. Dr. Hans Erich Hollmann, center and von Willisen is at the far right, Dr. Theo Schultes is second from left. This pictures, taken in 1935, shows Hollmann and Schultes consulting for the GEMA Company in Berlin, Germany. Hollmann and Schultes were the best of friends and had both graduated from the Heinrich Hertz Institute. It was at the GEMA Company that modern radar was invented. Notice the parabolic antenna on the ground. Photo courtesy of Harry von Kroge.
The Freya FuMG 39G was the first operational early warning radar defense system. Before the beginning of WWII, in 1938, eight of these units had been delivered by GEMA and deployed along the German border. The early versions had a range of 60 km which was later increased to 120 km. Azimuth accuracy was 1.5 degrees and better. These sets operated on a 1.8-2.0 meter wave length.	For gun laying, a more accurate radar with a more concentrated beam, than the Freya was developed by Telefunken. This radar, called the Wuerzburg FuMG 39 operated on 50 cm wave length and had a range of 25 km with a range accuracy of 25 m, an azimuth accuracy of 2 deg and an elevation accuracy of 3 deg. A rotating dipole antenna and a pulsed radar was used. 20 of the units were delivered by 1940 to the Ruhr area. By the end of the war, over 5,000 units of this and upgraded models (Wuerzburg D) had been in deployed in Europe.
Measured performance of early radar sets, distance and altitude in km.1. Wassermann FuMG 402 over water.2. Jagdschloz FuMG 404 over land.3. Freya FuMG 418 kW.4. Wuerzburg-Riese.5. Wuerzburg-Riese with GEMA accessories.	Above is a Wuerzburg-Riese, FuSE 65 built by Telefunken which used the same parts as the Wuerzburg D. With a parabolic antenna, diameter of 7.4 m, a range of 80 km could be achieved. Azimuth accuracy was 0.2 deg. and elevation 0.1 deg. The radar was designed to guide night fighters close enough to the attacking bomber for the pilot to see it visually or to locate it with his airborne "Lichtenstein" radar.
On the left is a Wassermann. Tower heights were from 40 to 50 meters. Range was 300 km. Built by Siemens in 1942. The early sets operated at 120-158 MHz and 100 kW. Later versions at 250 MHz and 800 kW.	The Jagdschloz FuMG 404 was designed with GEMA systems in 1937. It was produced in 1943 by Siemens & Halske. It operated on a frequency of 158-240 MHz. These frequencies could be changed so that the reflection of chaff could not be seen. 62 units were built.