ESM in WWII

[Francis Marliere]

Gentlemen,

I have a question about detection of radar emissions in WWII (ESM as we call it nowadays). I'd like to know if Scharnhorst in late 1943 could detect allied radars ? In one hand, one can read that Scharnhorst had a passive FuMB 4 Samos set (and may be a Sumatra one), but in another hand , he didn't detecct Sheffield's radar during the battle of North Cape.

Thanks for your help

[José M. Rico]

Hello Francis.
Take a look at this thread: viewtopic.php?f=36&t=2677

[Dave Saxton]

The Scharnhorst did detect the radar emissions of Sheffield or other radar emitted from Burnett's cruisers nearly 40 minutes before the British located Scharnhorst with their radar. This was the reason Scharnhorst had turned around and became seperated from the German destroyers. Scharnhorst was following about 10 miles behind Johennessen's destroyers as they searched for the convoy on a westerly course. When the Scharnhorst's radar detectors detected British radar from the south or south east, Bey turned the Scharnhorst toward that direction.

The KM had been using radar detectors to snoop possible enemy radar from the beginning of the war. The NVK had radar detectors set up as soon as France fell along the coasts of the North Sea and the English CH. The KM knew about Chain Home but didn't inform the Luftwaffe. The AGR Protocols contains the record of when the KM had detected enemy radar and on what wavelengths. When it became obvious that the British were locating U-boats with radar in 1942 the Metox was provided as a inexpensive, mass produced, radar detector in lue of the more expensive equipment already in use aboard surface units. Some ships such as Tirpitz had passive radar detectors by no later than Jan 1942.

The code names of the radar detectors used on surface ships were:

Samos (down to 60cm)
Wanze (Also down to 60cm and automatically cycling through the wave lengths) Wanze II down to 25cm, IIRC
Fanoe (from 70cm to 20cm)
Naxos (9cm -and 3cm harmonics)
Naxos -T (3cm -20cm)
Naxos-Z (3cm -12cm)

Antennas feeding these detectors were:
Bali
Sumatra
Timor
Palua ( usually associated with the Wanze)
Naxos were combination units, but the built in atennas had the code namas:
Cuba
Cuba-II
Mueke

[Dave Saxton]

The Germans assumed the British also had radar detectors, and indeed they did. This is why the Germans became so very concerned about the careless use of active radar, which would have usually resulted in a mission kill for them if they gave themselves away through careless radar emissions. The Allies were usually in a different mission role. The Germans and the British had been playing the ESM cat and mouse games for a long time prior to late 1943.

[Francis Marliere]

Jose, Dave,

thanks a lot for your kind and quick answer.

Best regards,

Francis

[RF]

Detection of British radar's by the KM didn't do the Germans any good either tactically or strategically.

[Dave Saxton]

Well the Metox did save scores of U-boats from Aug 1942 through April 1943.

We know from Luetzow’s KTB that Naxos equipment was used to identify and help locate Russian installations ashore, and gave early warning of Russian air attack, while operating with Prinz Eugen late war. Once Russian radar ashore was detected and identified via ESM, it was counter illuminated and targeted by active radar in conjunction with forward air control, and then usually destroyed via ship to shore artillery.

German patrol bombers late war used Naxos to help locate Allied ships and convoys. If the weather was poor they would then precisely locate the enemy via Hohentwiel airborne active radar which had a range of 150 km from an airborne platform.

ESM was also used by S-boats, T-boats, and destroyers with some success in the Channel and North Sea.

It’s true that the potential advantages of the German detection of British radar by heavy surface forces wasn’t really given a chance to be realized, but this was because in both cases the tactical commanders botched it.

The key to using ESM tactically is to not rely on it completely like Bey did, but to use it in conjunction with active radar and other sensors -using judgement and skill.

Howse included some input by Adm. Sir Jeremy Black on the RN use of radar during the Falklands:

Electronic surveillance had made phenomenal strides between 1945 and 1982, such that radar was often switched off rather than risk its detection.

On May 2nd there was intelligence of impending attack by the Argentinian aircraft carriers Veintecinquo Mayo, and two Invincible Sea Harriers were launched on a surveillance mission. They flew low level, their radar switched off, relying on their passive wave receivers. When Flight Leader Mortimar was at 150 miles out he climbed as briefed and switched on his Blue Fox radar to reveal a group a group of four or five ships less than ten miles ahead. The Argentinians who must have been radar silent, responded immediately by illuminating him with their fire control radar, which was the GO9, as fitted in the British destroyers, but also the Argentinian Type 42s. Mortimar detected their beams immediately and dived to break away……Despite the technological advances both in radar and electronic surveillance, identification remains a difficult area, particularly in the highly charged politico/military atmosphere leading up to and continuing into a period of warfare. In more recent years both the shoot down of a Korean airliner by the Soviets and the shooting down of an Iranian airliner by US forces in the Persian Gulf have sent serious ramifications through diplomatic channels. In 1982 the Argentinians used a civilian Boeing 707 to survey British forces steaming between Ascension Island and the Falklands. In such case neither the characteristics detected by ESM nor radar emissions could identify the aircraft in its military role. Even type identification was far from positive. In the event we relied on the pulse patterns and Boeing 707 radar search profile to identify the aircraft as hostile and even then they were protected by the rules of engagement.

This was where ESM and radar were going to during WWII and the Germans were ahead of the curve. There are strong parallels to these Falklands accounts and the Luetzow’s operations during the battle of Barents Sea. The Luetzow approached with active radar switched off but switching it on every ten minutes for two minutes. Luetzow switched on its active radar to locate and target the convoy when the reception of enemy radar reached specified signal strength. But then because Stange was unsure of the identity of the radar located targets, he failed to take advantage. Had he done so, the Convoy would have likely been destroyed and Barents Sea would have been great German victory brought about by their radar technology.

[RF]

Your last sentence Dave highlights my point about the radar technology not doing the Germans much good.

I also believe that for many of the U-boats saved by Metox by early 1943 it was only a stay of execution.....