Big is better
> military are high powered, heavy, and demanded large antenna arrays
Because military radar isn't used to detect whether the general in the next room has fallen of his/her's perch. The problem with RADAR is that it suffers from an inverse squared, SQUARED law. I.e. 1 / (r ** 4) power/distance relationship. The signal going out from the transmitter is the normal 1/r^2 degradation with distance to the target and the signal reflected off the target (assuming it's "playing the game" by not being stealthy) comes back with the same power::distance ratio. Hence the need for massive amounts of power, huge receiving (and transmitting) antennae and therefore large installations.
I'm sure that given their expertise in the area, the military are more than capable of making a bitsy little version - and could / would / probably-have if there was a requirement ... say from the clandestine services.
Now where did I put that foil-backed wallpaper?