Some data on German AA radar R&D

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Dave Saxton
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Some data on German AA radar R&D

Postby Dave Saxton » Mon Jan 19, 2015 8:58 pm

The Germans hit a home run with the Wuerzburg conical scanning radar design for aircraft tracking and Flak control. But it could not be mounted on a ship easily. It required a fully stabilized mounting system and a smaller antenna. Euklid was intended to be the navalized Wuerzburg. Looking at some of my notes, some test results during the R&D:

Wuerzburg range accuracy: 25 meters, The Kriegsmarine previously obtained this result in tests and the USAAF also obtained 25m accuracy with a captured set.

Mannheim's range accuracy: 10m

Max aircraft tracking range...wave top.........300m altitude.........500m
Flakleit G (Seetakt) 80cm......8km..............20km...................38km
Wuerzburg D 50cm..............9km..............21km....................42km
Eisvogal 21cm....................6km..............18km....................17km
Wuerzburg 9cm...................15km............30km....................22km

Compared to decimetric wavelengths there is a 15% range attenuation through snow with 9cm wavelength.

27cm has significantly greater detection range to aircraft compared to 9cm, all other factors the same.



Also the Germans recovered an American 3cm airborne radar intact at Meddo Belgium in April 1943 and tested it vs U-boats.

It could detect the periscope of a U-boat from 9km (at 8,000 feet altitude)
A surfaced U-boat from 18km
A large steamer from 150km (8,000 feet)

This is how they knew the typical ranges that U-boats could be detected by Allied ASV and that Hohentwiel-U could detect the aircraft before the aircraft could detect the U-boat. U-boats were ordered to always operate Hohentwiel (if equipped) when on the surface, for air warning.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

Thorsten Wahl
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Re: Some data on German AA radar R&D

Postby Thorsten Wahl » Tue Jan 20, 2015 10:20 am

Note on Mannheim
M used (As far as i interprete the description in the service regulation) pulse compression
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Re: Some data on German AA radar R&D

Postby Dave Saxton » Tue Jan 20, 2015 4:20 pm

Thorsten Wahl wrote:Note on Mannheim
M used (As far as i interprete the description in the service regulation) pulse compression

Indeed the German use of coherent techniques was one the reasons why German radar development took the course it did, which was different from the Allies-at least during the war.

For example, Seetakt originally had a magnetron transmitter but it had to be dropped in favor of triodes because the fine ranging system would not work properly with the frequency instabilities of magnetrons. Seetakt used a central impulse geraete that marked both the transmitted and the echo pulses according to a master oscillator. Time was measured by comparing the phase of the echo pulses to that of the master oscillation. Any radar systems engineer today would instantly recognize this as a coherent technique to improve discrimination for range without resorting to very short pulse widths.

During the Cold War it became apparent that the west needed the West German radar expertize to stay ahead of the Soviets. A treaty was signed in Paris in 1955 that allowed West German companies like Siemens and Telefunken and AEG to ressume radar R&D. The West German firms quickly became recognized as the leaders in development of advanced coherent techniques such as pulse compression.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: Some data on German AA radar R&D

Postby Thorsten Wahl » Wed Jan 21, 2015 12:51 pm

U
-boats were ordered to always operate Hohentwiel (if equipped) when on the surface,

for clarification
as Hohentwiel consists also of a passive radar receiver,

should H. be used in active or passive mode?
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Re: Some data on German AA radar R&D

Postby Dave Saxton » Wed Jan 21, 2015 3:44 pm

The active Hohentwiel. The passive dipoles on the back side were technically given another name (Palau) going to either Samos or Fano passive sets. Only active radar could give the range of the intruder.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: Some data on German AA radar R&D

Postby Paul L » Mon Mar 02, 2015 6:56 am

If these Radars were also passive why the need to also develop a range of radar detectors?
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Re: Some data on German AA radar R&D

Postby Dave Saxton » Tue Mar 03, 2015 1:54 am

No, the Hohentwiel radar electronics were not passive but in many cases a pair of passive dipoles were mounted to the back side of the Hohentwiel (and also the FuMO30) antenna. This was the case on U-boats equipped with active radar. These passive dipoles could feed signals from enemy radars to a passive receiver like the Metox, or the Samos, or Wanze...ect...
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.


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