Common volume modelling for the prediction of interference due to scattering by hydrometeors

Factors affecting the calculation of common volumes of radio links subject to rain or ice scattering are discussed. Sidelobes modeled by envelope patterns may result in significant increases in the effective common volume. This effect is most noticeable when considering situations involving a terrestrial beam with its associated high level sidelobes. In considering sidelobes, the width of the antenna beams has increased to such an extent that assumptions made when developing interference models may be questioned. It is shown, for realistic geometries, that the effects due to the refractive index height profile may significantly alter calculations of the effective volume.