Is there a background microwave radiation at shorter wavelengths that could be made into a camera that could see through clouds too? microwave is too long wavelength to make a small camera.
Yes, multistatic radars are already in service. An advance on the concept is that the active transmitter can be placed outside anticipated weapons range and those within range are merely passive receivers.
There have been proposals to build such systems that use 'oblivious' transmitter sources such as commercial radio broadcasts.
ITAR assumes the US leads the world in technology, and actively prevents us from catching up if we don't.