Microwave communication beyond the horizon

Refers briefly to several first-time demonstrations of microwave communication and deals with certain aspects underlying the choice of equipment to ensure reliable performance. Basic attenuation curves for tropospheric propagation following a coordinate system are given for five frequencies between 250 and 5000 Mc/s. These curves cover: (1) Region A which represents plane-earth reflection with a reflection coefficient of unity; (2) Region B for the region between a clearance equal to the first Fresnel zone and grazing incidence; (3) Region C where the diffracted field prevails; and (4) Region D for tropospheric propagation beyond the horizon. Further curves are given covering beyond-the-horizon conditions using data by Bullington. Another set of curves shows the transmission levels as a function of frequency for equal performance over a free-space line-of-sight path using certain specified aerials. The corresponding curves for beyond-the-horizon propagation are also given. These curves are discussed and their practical application considered. 18 references.