I am trying to get some exact details of Window the radar countermeasure used by the RAF in 1943 against the German Wurzburg and Freya air defence radars. The Wurzburg radars operated on a wavelength of 53cm so the individual strips, cut to exactly half a wavelength, would have been 26.5cm long or about 10.5 inches. I need to know the width of the strips and the material from which they were made. I understand that it was not aluminium foil but rather a paper impregnated with metal particles, I would imagine that aluminium was in very short supply and too valuable to be scattered all over the sky! Any information, a photo or a sample would be most welcome.(I should be so lucky, but surely someone picked up bucket loads of it - we dropped it all over mainland Europe !!) I am compiling an exhibit on the use of Window and Chaff during WW2 for our local aviation museum (Solway Aviation Museum at Carlisle Airport) and it's invention, development and finally deployment by the RAF in July 1943 in the night raids on Hamburg. The express permission of Winston Churchill on July 15th 1943 was needed to use what was then regarded as a Secret Weapon.