"Most Secret War" British Scientific Intelligence 1939-1945 by R V Jones (ISBN 0 340 24169 1) is also very good. . .. .Talks about early British a/c detetion methods (including sound and heat), but mainly the battle with the German systems (Knickebein, Wotan etc) especially the jamming and deflection of the beams.. .. .Gee, Oboe, H2S etc are also dealt with in a very informative manner on the British side, moving on to the V-1 and V-2's towards the end of the war. Fascinating!