Is terrain scattering a significant contributor to interference by personal communications satellites?

The power flux on earth that is expected to be generated by Personal Communications Satellites, will be orders of magnitudes higher than that of the present satellite service. Interference to other services, e.g. terrestrial microwave links, radio astronomy telescopes, cannot be locally coordinated, and becomes a major concern. Flux scattered from large areas of ground surface and cover - into the antenna main beam and near sidelobes, may cause higher interference than direct coupling into the antenna. This mechanism, previously observed in terrestrial systems, is less angle-dependent and harder to mitigate. Parametric study of the interference, based on a simple model, interrelates this effect to other observed phenomena, to infer the potential of strong interference. Considering the impact of such interference, measurements and scattering modeling efforts are proposed, in order to validate the observations and characterize. scattering of different environments.