First of all sorry if this is off topic, I couldn't find a group on radar.
I was wondering why radar guided missiles use such a high frequency. Looking at a graph I have showing atmoshperic absorbtion of radar waves; there are two very high peaks (indicating high absorption) at60GHz and 120GHz. This is due to resonant frequencies of atmospheric molecules. The hellfire missile's radar seeker operates at 94GHz and the Apache Helicopter uses a 35GHz radar. Absorption at the helicopter's and missile's frecuencies is fairly similar so it can't be anything to do will design operating range.
It must be something to do with either antenna size or resolution, but no idea which or why. Can anybody please point me in thre right direction?
Thanks for any help Adam