Question About Radar (and Radar Jamming)

Scenrario:

A squadron of German bombers (probably wrong choice of words) make their way to somewhere such as France. They want to bypass the French radar. Was there any sort of successful jamming device? And this isnt restricted to the French, this is saying was there ever any successful radar jamming device?


Or perhaps some way of decieving radar. Nowadays it is probably possible to jam a radar for the second world war... could anyone tell me how it would work? Perhaps to a link to a helpful page?

 

The French did not possess a working radar system prior to their fall. The most they had were a handful of experimental systems.

Radar jamming was done extensively during WW 2. Most of the jamming systems in use were Allied.

The typical methods for jamming were:

Noise: Systems like Mandrel, Rug or, Carpet put out a large signal overwhelming returns and blinding the radar.
Deception: A system like Boozer that was a repeater. It gave out signals similar to that of a bomber return signal making it appear that there were several bombers where there was just one.
Chaff / Window: The use of metal foil strips to create a large radar target and hide the actual aircraft.
Just about every imaginable method was tried during WW 2 at jamming any and all electronic signals. Of course, this barely touches on the subject.

 

So it was possible to hide something such as a bomber squadron?

or at least distort the radars image and not allow the operator to pinpoint where the incoming aircraft were

and thanks for the reply.

 

Yes. RAF bomber command was probably the premier air force in doing this. By 1944 they would have typically:

Put up a Mandrel screen across the North Sea to blind German search radars while their aircraft became airborne and formed up.
After crossing through the Mandrel screen ABC and Jostle radio jammers would have begun to literally make German fighter communications virtually impossible.
There would be several diversionary strikes using jamming to look like big bomber groups.
The main strike(s) would have jammers aboard to blot out search and fire control radars for flak as well as night fighter radar. The group would begin to drop chaff as they approached the German coast in huge quantities.
British night fighters would prowl using systems like Serrate to track down German nightfighters that ran their radars.

The US would have had large numbers of Carpet and Rug jammers along with Chaff to jam German flak radars. The US didn't worry so much about fighters and direction as they operated in daylight making this largely irrelevant.

The Germans would return the favor operating ground jammers that made it hard for the bombers to use systems like Gee or H2S for navigation.

As Adolf Galland himself said to Göring in mid 1944 "Today the nightfighter achieves nothing! The enemy's jamming blots out all electronics leaving us blind!"

 

Flying at tree-top level until close to the target before climbing to bombing altitude,would'nt that work?

 

Yes, but there are many technical problems. One of which is that along the route aircraft routinely abort for mechanical trouble. In early 1943 a squadron of fast B26 bombers approached the Dutch coast completely undetected. Then one aircraft lost a engine. The pilot could not maintain consistent altitude, so he pulled up to avoid hitting the sea. This instantly triggered a alarm of the German AA defenses. This led to the second problem. Bombers at low altitude are extremely vulnerable to small caliber AA weapons. In the case of the B26 raid none of the remaining aircraft made it back to Britian. A 100% loss of those that crossed the Dutch coast. A group of fast LeO45 bombers attempted to interdict the German tank columns in the Ardennes on the 11th & 12 of May 1940. The German light FLACK & MG massacred them with just a few minutes warning.

Another problem is the ammount of training needed for extreme low level flight. Its extremely demanding and losses from miscalculations are significant.

Finally there is the problem of enemy ground observation stations spotting the bombers. Even a crude system like those early in the war were effective. And, a good system could create diasters like the Ploesti raid.

Low level tactics can be usefull under specific circumstances, but they are not suitable for massed bomber attacks.

 

The Raf used different systems. One of these was simply to drop small pieces of aluminium, they would immediately be detected and confuse the German radars. This was calle dwindowing. An other system was THE ABC onboard jamming device used for instance by 101 Squadron. A special operator would jam the German radars and make sure the bober stream was not detected. When the Germans discovered the A channel, the operator had a few seconds to switch to the B or to the C channel.

 

The electronic war (I.e. the development of radar, radio jammers, radar jammers and counter-measures) is one of the real fascinating aspects of the European air war - one side would develop a technology, the other side would perfect a counter to it, an alternative or improved technology would be developed and on and on and on throughout the war. The main combatants in the electronic war were the Germans and the British… the electronic war was nowhere near as sophisticated in the PTO (I have no idea what went on in the Eastern Front radar-wise). The following chart (adapted from ‘Dirty Little Secrets of World War II’ - pp 202-207) gives a chronological rundown of the different technologies/counter-technologies that were developed through the war years.

DATE__ USER___ ITEM ___________FUNCTION
===================================================================
2/40___Ger____Knickebein________Navigation beam
6/40___Ger____Wurzburg_________Detection Radar - 40 km range - flak control
9/40___Allies___Asperin__________ Knickebein jammers
9/40___Ger____Freya_____________Improved detection radar - 120 km range-no altitude
10/40__Ger____Wurzburg II_______Pair of radars-1 tracks bombers, other tracks interceptors
9/41___Ger____Wurzburg Reise ___Improved Wurzburg - 120km range
2/42___Ger____Lichstenstein______Airborne radar - night fighters - 200 - 3,000 m range
3/42___Ger____Mammut _________Detection radar - 330 km range - no altitude
3/42___Ger____Wasserman ______Detection radar - 240 km range - altitude detection
3/42___Allies___Gee ____________Airborne navigation from ground transmitters
6/42___Allies___Shaker __________Gee-equipped Pathfinders provide aiming points
8/42___Allies___Moonshine _______Amplified 'Freya' returns - for feint operations
8/42___Ger____Heinrich __________'Gee'-jammer; rendered Gee unusable by 11/42___
11/42__Allies__Mandrel ___________airborne 'Freya'-jammer
11/42__Allies__Tinsel _____________electronic communications jammer
12/42__Allies__Oboe ______________groundbased bombing radar - 430 km range -
1/43___Allies__H2S _______________ground mapping airborne radar - not debugged ’til 11/43
3/43___Allies__Monica _____________tail warning radar -range 1000m - warned of tailing a/c
3/43___Allies__Boozer _____________Radar receiver - warned of Wurzburg or Lichtenstein
6/43___Allies__A1 Mk 9 ____________Improved radar for night fighters
6/43___Allies__Serrate _____________Detected Lictenstein
7/43___Allies__Window _____________tinfoil strips - created an electronic ’smoke screen’
8/43___Allies__Special Tinsel ________Updated communications jammers
9/43___Ger____Naxburg ____________detected H2S
10/43__Allies__ABC ________________Airborne jammers - jammed German ground control system
10/43__Allies__Corona ______________Sp. Tinsel jammer - sent out false instructions to German Fighters
10/43__Ger____SN-2 _______________Night fighter radar - immune to Window - range 400-6,000m
11/43__Ger____Nurmburg ___________Modified Wurzburg - allowed detection through Window
11/43__Ger____Flensburg ___________Airborne Monica detector
12/43__Ger____Dartboard ___________sent coded jamming communications to fighter pilots
1/44___Allies__Oboe2 ______________Oboe with a new type of radar signal
1/44___Ger____Naxos ______________Airborne H2S receiver - used to locate H2S equipped bombers
4/44___Ger____Jagdschloss _________Jam-resistant ground radar - 150 km range
4/44___Ger____Egon _______________Jam-resistant fighter control radio - range 200 km
8/44___Allies__Jostle _______________Airborne multi-frequency ‘barrage’ jammer
9/44___Allies__Window 2____________jammed SN-2
10/44__Allies__Serrate 4 ____________detect and locate new SN-2
12/44__Allies__Perfectos ____________triggered German IFFto located enemy fighters
12/44__Allies__Micro-H ______________Backup alternative for Gee

As can be deduced, there were a lot of real smart people on both sides working all throughout the war to develope these technologies and their counter-measures.

Interesting stuff....at least, I think so!

-whatever

-Lou

 

I recently finished an incredible book by Robin Neillands called The Bomber War. It is extremely informative and just an incredible source of information with everything you could ask for on the development of radar and radar jamming and counter radar systems. If you can add it in there somewhere it would be a great one for you!

 

Lou that chart is an incredible summary of the radar race. fascinating!

 

Hey, it gets even better. When a Luftwaffe Ju88G-1 of 7/NJG2 landed by mistake at RAF Woodbridge on July 13th 1944, their FuG 25A IFF system was compromised.

The British "boffins" developed and fitted a system called PERFECTOS to their Mosquito nightfighters. PERFECTOS sends a radio signal that triggered an automatic response from the FuG 25A - i.e. spoofing the German IFF into identifying itself and telling the RAF nightfighter where it was! This technique allowed detection and tracking of German nightfighters at ranges much greater than the RAF nightfighter's AI radars.

Numerous German nightfighter few prey to Moquito nightfighters of the RAF 100th Group equipped with PERFECTOS.

Much later, when the SRO-2 IFF system on the MiG-21 was compromised (by a defector), the USAF began equiping their EC-121 "College Eye" AEW aircraft in 1967 with QRC-248 which could track the SRO-2 IFF signals from MiG-21. Initially, QRC-248 only passively tracked the signals from SRO-2 sent when it was triggered by a North Vietnamese IFF interrogator. Later on, College Eye was allowed to use QRC-248 to actively interrogate and trigger the SRO-2 to respond. That was how MiG-21 were identified as "Blue Bandit" by College Eye.

Later still, a smaller system, "Combat Tree" was developed and fitted to USAF F-4D Phantoms. This system (APX-80) was used to good effect against MiG in the Arab-Israeli conflicts by the Israelis and during the Iran-Iraq War by the Iranians.

 

The problem with such systems is once the enemy suspects they are compromised they either turn them off or replace them. Perfectos never lived up to its potential for this reason. The main user 100 Group RAF, had alot of difficulty turning Perfectos intercepts into interceptions. Their main ESM was Serrate a system that tracked SN 2 radar signals.
The same goes in later wars. Once the enemy knows you are tracking a particular system they will adapt and you are back to square one.

 

German accounts certainly suggests that they realized or at least suspected that FuG-25A was being spoofed. Nevertheless, RAF accounts do list quite a number of nightfighter kills where PERFECTOS played a hand. Switching off the IFF made it much harder for GCI control and could also put the German nightfighter at risk of being attacked by their own side.

It was also the fortuitous capture of the 7/NJG2 Ju88G-1 at RAF Woodbridge, that allowed the RAF to get Serrate IV tuned to the much longer wavelength of SN-2. Previous to that, the 100th Group nightfighters had not been passively detect the SN-2. Older versions of Serrate was tuned to the higher frequencies of the older Lichtenstein AI sets.

R.V. Jones recounted in Wizard War how they had figured out that the new SN2 AI set was using a much longer wavelength from USAAF gun camera stills of Ju-88 and Bf-110 nightfighters equipped with the much larger antennas of this radar. The nightfighters were helping out during daylight raids in May 1944 when they were attacked by USAAF fighters.

That helped ELINT / Ferret efforts to focus on the likely range of lower frequencies but it was not until SN2 was captured at RAF Woodbridge that its precise operating frequencies were discovered.

With encryption and changing of codes, IFF is much more secure these days. However, during the days of the hard-wired systems, it was much harder to change. Certainly, you could switch off the system - but that is extremely hazardous when operating within range of surface-to-air missiles. The Soviets certainly took a lot longer to realize that SRO-2 was compromised. According to Iranian accounts, Combat Tree was used to good effect well into the 1980's during the Iran-Iraq War.

 

And nowadays Hendon has this beautiful Ju88 on display! Thanks for the addtionnal details. The funniest is when I talk to German veterans they mostly say they hardly used them and got theri victims by sight whenever they could.