"It was originally designed to be deployed on low-flying aircraft, eg AC130."
Thanks for the technical oriented comments. So it was originally designed for military use as apposed to civilian crowd control. OK. So based on your description of how it works, that is, some narrow band of microwave, most probably, is aimed at a surface. Fine. If, the beam can penetrate "dry clothing", not lose sufficient amounts of joles, due to energy absorption by the clothing, and still have adequate "beam power", to sufficiently heat up water molecules within the beams cone as it projects unto the person's skin, and make them say ouch! Fine. I have no problem with that. But are they going to just stand still? And what if they are armed with fire arms?
Are, lets say fifty angry people going to just stand still as a few soldiers scan the beam back and forth across their mass of bodies? What happens when they start to disperse?
How many have guns? What about controlling a few thousand, and perhaps twenty in the middle of the pack suddenly run forward and open up on our guys with fire arms.
It would appear that our guys will have to have teams of standard infantry men with M4's etc., and other teams that carry the heat guns.
Perhaps I am being to negative about the heat guns potential in such scenarios. Guess we will find out how well it works in due time. I hope I don't read about our soldiers and Marines getting KIAed for lack of proper protection during crowd control.