On the Worst Case Trajectories of Microwave Links Above Belgium

It is common that the national authorities impose large consultation zones around microwave links [1]. When those areas are free of obstacles there is no problem, but usually they are considered as exclusion zones. Those large zones are inspired by the fact that the obstacle for which the authorisation is requested may not be the only one, especially in the case of wind turbines. The national authorities (for Belgium BIPT/IBPT) impose limitations on the projections of the links in a horizontal plane, usually 3 times the largest size of the first Fresnel ellipsoid. In this paper we will investigate the 3D case to allow more lenient criteria to be applied.