The set was also produced in the US as the AN/APS-13, but used primarily on late-war fighter aircraft like the Republic P-47 and North American P-51.
These had to be withdrawn over Europe in 1944 when it was learned the Luftwaffe was homing in on their signals using the Flensburg radar detector.
During the same time, the Luftwaffe began adding additional rearward-pointing antennas to their night fighters as an ad-hoc tail warning radar to provide some protection from these dreaded "Serrate" intruder flights.
These systems also have the advantage of working against air and ground radars, which became important as the main anti-aircraft threat moved to surface-to-air missiles (SAMs).
A new class of tail warning radars emerged in the 1980s, primarily as a counter to SAM fire.