They would be a fundamental component of Solar Power Satellite systems.
The SPS rectenna can sited almost anywhere, but although the microwave radiation at low levels is harmless, public fear of microwave radiation exposure might cause them to be sited in remote areas.
One interesting site might be the Chernobyl Zone of Alienation, an uninhabited radioactive area surrounding the Chernobyl nuclear reactor in the Ukraine which sprayed lethal radiation over a large area in 1986.
This is zone is patrolled by the Ukrainian state security service to make sure that no unauthorized people enter, getting entry permits is possible but difficult. Yet the area is close to large population centers, and large industrial consumers of electric power. Also, it was a major hub for electricity distribution, from the reactor. So infrastructure already exists to connect a rectenna directly to the Ukranian power gird.
The central hot zone has a radius of 30 kilometres, which is large enough to accommodate several SPS rectennas, with potential for tens of gigawatts of power delivery.
There are other sites of nuclear tests and disasters which might be suitable. For example, Kazakhstan had some nuclear test sites, also in Nevada USA. A big Soviet nuclear waste dump in the Urals exploded in the 1960s, that is another large exclusion zone.
- September 29, 1957: At Kyshtym in the Soviet Urals. Kyshtym is near the Chelyabinsk-40 nuclear complex, also known as "Mayak" ("beacon" in Russian), where on 29th September, 1957, a violent explosion involving dry nitrate and acetate salts in a waste tank containing highly radioactive waste, contaminated an area later called the "Kyshtym footprint". The explosion resulted from a failure of the cooling system of the tank. About 800 km² of land were taken out of use, and 82% of this area has now been taken into use again for forestry and farming.