Multiple RF channels bi-directional UHF amplifiers one radiating RF transmission line

This paper describes the design parameters of a six (6) channel UHF radio communication system consisting of a single, 12 mile radiating RF transmission line network and 45 bi-directional RF amplifiers. The amplifiers will boost the UHF RF channels, in both directions, and provide the necessary transmit-receive RF isolation to permit the use of standard 5 MHz RF separation between Transmit and Receive UHF RF frequencies. The UHF RF channels will be used for hand held portable radio communications, for point-to-point data circuits (computer terminals) and for alarms on critical devices (fans, conveyor belts, elevators, etc.). This system is presently being installed and tested in an underground coal mine that is 650 feet below the surface. The design parameters were based on previous tests of a prototype system (two bi-directional RF amplifiers and 5000 feet of radiating RF transmission line) in the same coal mine.