|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
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
||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
|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.
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.
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.