Radio Track and 'J' Beams

Homing Beams (with dots to the left, dashes to the right), used by the RAF in WWII were of three types:
An excellent example of (2) was via the Medium Frequency 'Leader' beacon at Derrynacross / Lough Erne which UK bound aircraft could pick up over the Atlantic. Once over Ireland aircraft could then pick up the RTGs from Prestwick, Squire's Gate, Silloth and Valley.

'J' Beams were RTG transmitters located in the UK beaming a homing signal into enemy occupied territory. Their main function was to confuse the Germans and hopefully throw them off the scent of the RAF's new GEE navigational system (The 'J' was deliberately chosen as it is very phonetically similar to 'GEE'). The beams were rotatable, and for a long period were used successfully by the RAF to find their way back to the UK.

I haven't found a photo of one, but they would be similar to the Luftwaffe's Knickebein aerials - a huge turntable-mounted array, several metres high and tens of metres in width to produce the required narrow beam.

They became operational between May and September 1942, and there is evidence that Luftwaffe Signals spent some effort in jamming them, whilst ignoring the important GEE transmissions. They were evidently flattered that the British had copied an valuable German invention!

From AIR14/1257, the known stations were:

Lat/long co-ordinates given - not sure about stations E, G-I (if they existed). I couldn't easily locate any of the sites in Google Maps etc. (A challenge for someone )

The other Air Ministry ruse to confuse the enemy scientists was by allocating misleading type and serial numbers to the aircraft electronic equipment. Hence T/R 1234 wasn't necessarily a Transmitter-Receiver. The Germans were naturally scrupulous in their numbering which was of great assistance to British engineers. A Luftwaffe transmitter type '1234' was definitely a later version than a type '1233', and serial number '999' was definitely manufactured before '1012'. This was not to be the case with later British equipment.

Graham

Two links

Picture of a Knickebein Aerial, Article , with drawing

Just noticed the TNA lat/long for 'Whitlands' above is wrong. The NGR for the hamlet (not the RTG) is SY306911, approx 50/42N 2/59W

EDIT: Those links are now dead. Here are two more

www.battlefieldsww2.com/radiobeacon-stations-knickebein.html

www.alfamontreal.info/Articles/Beams.pdf



Graham

PNK;30728 wrote:

Carnaby, Lyme Regis seems to have shifted a bit north!
Any idea how big the site would have been in plan form?.

Error now corrected above - your message slipped in just I was correcting the reference!. There is only one TNA file relating to J Beams. I wonder if they were dismantled soon after the jamming began - possible by 1943?

Graham

I think I may have located the remains of the one at Ravenscar, which is a very large circular pad, surrounded by a fairly low brick wall. I was never sure exactly what it was, but it sounds like it could be this. I have some photos of the remains, but haven't scanned them. I have found an aerial photo in Bing maps, but don't know how to link to it.

Cheers,

Ian

Ian, could you supply the NGR for the site - sounds promising?

Graham

The circular pad is at MR94/973013 . There is a radio mast very close to the NW and also some wartime concrete hardstandings . I visited this area last month and the view from here is excellent and well chosen as the site for a radar station.
This station is mentioned in the book Halifax Squadron, the wartime bombing operations of 640 Squadron, self published by Bill Norman . He quotes a then wireless mechanic at the RAF's Radio Track Guide Station Ravenscar as working with a Swab transmitter and also a Darkie TR9 set , the latter being used to give a bearing and distance to a prominent local feature, usually Scarborough.
Just down the coast at Bent Rigg Farm are the remains of a CHL radar station with several buildings still remaining; MR94/992008.

David wrote:

Just down the coast at Bent Rigg Farm are the remains of a CHL radar station with several buildings still remaining ; MR94/992008 .

Just a small point of pedantry. The site was not CHL but rather CD/CHL. Although it operated on a 1.5 metre wavelength, it had a different primary function and used very different structures.

The map reference is indeed the structure I was referring to. The pad must be about 30 feet in diameter.

Cheers,

Ian

The RTG site is HERE , and the second site is HERE

Thread on second site HERE

OT but referring to David's post #8, I guess the Swab was a Marconi SWB (short-wave broadcast) device manufactured in many forms. The BBC used 100kW versions for their Overseas Service during and after WW2. A few links - Dorchester Radio Station , SubBrits Ongar site , SWB type 8

Graham