[pgorczak]

Not trying to argue for the feasibility of space based solar power, but the inverse square law applies in the far field i.e. when the emitter can be approximated as a point source. Depending on the wavelength and the antenna size this is not necessarily the case: https://en.m.wikipedia.org/wiki/Fraunhofer_distance

E.g. for 3 GHz and a 500 m antenna, the far field starts at about 5,000 km