Radio propagation beyond the horizon observed at 1 and 3 GHz compared with predicted reflections from random rough layers

Measurements from the scaled tropospheric scatter links at 1 and 3 GHz Stockholm-Mora have given unexpected results. As a rule, the variation in received signal level in decibels of the half-hour median is three times higher at the lower frequency than at the higher frequency for comparatively low signal levels, whereas for high signal levels it is almost only the signal level at the higher frequency that shows variations. The measurements are compared with the theory of reflections from random rough layers with a linear refractive index step and a length , which is shorter than the Fresnel zone and shorter than the glistening surface. The theory is in very good agreement with the measurements.