Microwave radio meteorology - Fading by beam focusing

The transmission performance of terrestrial line-of-sight microwave radio systems is significantly affected by fading caused by anomalous beam propagation. A better understanding of microwave beam propagation during fading events is needed for improving estimates of fading occurrences and for designing equipment to combat fading. The present investigation is concerned with four fading episodes from the period July through September 1981 using propagation and meteorological data obtained at a propagation test site. The results indicate that some of the fading observed may be caused not by multipath propagation, the most commonly cited fading mechanism, but by focusing effects produced by nonlinear refractive index profiles in the lower 200 meters of the atmosphere.