A theoretical method is required for prediction of mean field strength in land mobile radio systems, instead of the conventional empirical methods. Feasibility study of theoretical prediction using the ray-tracing method, was made in a 1.2GHz band for a model of a small-cell system. Theoretical values showed better agreement with the measured, when diffraction around the side edges of a building is taken into account. Comparison between mean field strengths in summer and winter suggested the seasonal variations in attenuation due to trees.

In order to evaluate multipath signal strengths reflected by mountain, a fundamental equation is derived for both cases where antenna beams are larger and smaller than a reflecting plane, assuming that reflection consists of absoption and scattering at the mountain surface. Absorption loss at a mountain surface was measured on a model propagation path by using sharp beam antennas to separately pick up the mountain-reflected signal.