Well that’s good. I can’t imagine how you would generate just one microwave.
On a serious note it seems that the author is trying to make this out to be a GREEN rocket engine because it will be SOLAR powered.
But that would seriously limit the rocket’s utility to space travel near the sun. The further from the sun the spacecraft gets the less power would be available from the sun.
Kidding aside, scientists have recently figured out how to make masers in a reasonable size and operating at room temperature. Given that a maser is the microwave equivalent of a laser, with it you can indeed produce a very tight and coherent microwave signal at a specific frequency.
Ditch the solar power. Plug it into a cold fusion generator and then you’ll really have something.