Propagation losses due to foliage at various frequencies

Fixed access radio systems have been proposed or implemented at various frequencies with subscriber antennas located either inside a building or on the roof. One important factor in the link budget and hence coverage probability is the propagation loss due to foliage. This can either be the effect of large clusters of trees along the path or of isolated trees close to the subscriber. While high resolution clutter, vector or digital elevation databases could show the larger clusters of trees, the isolated ones are commonly not resolvable at reasonable cost. Therefore there is a requirement to allow for individual trees in the link budget for some areas. We present results on the effect of isolated trees on fixed access links at frequencies from 3 to 30 GHz where we assume that the subscriber antenna is directional and roof mounted.