If you are looking at First airborne radar in the UK, then you will find plenty of references, but the Germans were far ahead at the beginning of the war and had a huge advance until 1943-44 where things reversed. . They had the first radar units of radar equipped night fighters and 360deg azimuth small antennas radars on the ground already in 1939-40. But not much documentation in English unfortunately. History is always written by the ones that win the wars. ..