It's not what you think it is! When I heard microwave gun, images of a funny laser gun that cooks food in a flash popped into my head. The Russians are developing a microwave gun that doesn't cook food, but actually disables drones and missiles.
The microwave gun is equipped with a heavy duty relativistic generator and reflector antenna, management and control system, and transmission system that gives whatever it's attached to a complete, 360-degree bubble of protection. The Russians are aiming this technology at drones and unmanned aircraft and missiles that rely heavily on radio frequencies.
These radio-controlled military tools would be rendered useless after the Russian microwave gun stuns it and would no longer be able to take video, photo or audio surveillance. They would not be able to communicate with the drone operators on U.S. military bases as well.