Propagation influences in microwave link operation

Basic characteristics of ground-to-ground propagation in the frequency band 50¿10000 Mc/s are discussed, with emphasis on the operation of point-to-point radio links. Practical applications of such know ledge are illustrated by appraisals of the use of flat radio mirrors for circumventing mountain obstructions on microwave radio links, and of the capabilities of large-aperture aerials and space-diversity systems in reducing fading. Ground reflections are shown to be a key factor in the performance of very short wave radio links and the influence of inhorno geneities in the lower atmosphere is also stressed. it is pointed out how statistical analysis of temporal and spatial signal strength variations can often reveal the nature of the propagation mechanism at work, while at the same time pointing the way to improvements in circuit reliability.