I don't have the information ready at hand--it's been years since I worked on this kind of concept--but the designs for microwave reception and transmission are well-understood. The beam is relatively dispersed, and picked up by a large antenna system on the ground. This ground antenna can be a mesh raised above the ground on poles over many acres. Mostly transparent to light, the area beneath it (which naturally is shielded from the microwaves) can be used for agriculture. Even birds flying through the area over the antenna would be unharmed.

The antenna system on the satellite has a feedback setup that shuts the system off if for some reason the transmitter is forced off the target area.

A nuclear power plant would be cheaper. But maybe not forever.