Quadruple-diversity tropospheric scatter systems

It is concluded that with a given set of present day uhf equipment limitations, i.e., transmitter power, antenna gain, receiver noise figure, etc., it is possible to utilize configurations of these equipments to advantage when tropospheric "sctatter" propagation is employed. Because of the Rayleigh distributed fading on tropospheric "scatter" circuits, significant improvements in performance can be achieved by employing the highest order of diversity reception possible. Using present operational equipments, with the exception of high power bipolarized feed systems, quadruple-diversity reception can be employed with only two parabolic reflectors per terminal. Essentially the same amount and type of equipment is required for the quadruple-diversity system as is required for a dual diversity system with standby equipment. However, the quadruple-diversity system utilizes the "operational spare" concept to advantage from both the equipment reliability and propagation reliability standpoints. With this system highly reliable multichannel communications are operationally feasible for circuits well over 300 miles in length.