its a microwave cannon ... basically for riot control ...
the idea was taken from microwaves heating up stuff combined with microwave communications ...
they used a microwave communication transmitter and boosted it so that it would heat up stuff in front of it without it harming people permanently, the radiation only penetrates about 1/64 in of skin so you would still have the possiblity of getting skin cancer ...
whats really odd is that the japanese tried this out during WWII , they had a much more effective cannon but it wasn't mobile and they didn't have the resources to generate enough power and put up enough stations ...
if you wanna hear about weird or cool weapons, im the person to ask