Microwave radio system for multichannel telephony and television in the 6-gigahertz range: I. basic features; II. solid-state microwave power generators;III. wide-band intermediate-frequency amplifiers; IV. cassegrain antenna; V. auxiliary radio relay ...

Describes the main features and individual parts of a system which provides 1800 speech channels or one TV channel, developed jointly by the Standard Telephones and Cables Ltd. In England, Standard Elektrik Lorenz in Germany and Bell Telephone Manufacturing Co. in Belgium. Solid state circuits are used not only in the baseband and IF (70 Mc/s) amplifiers but also in primary microwave power sources; variable capacitance diodes are employed as passive frequency multipliers, and only the transmitter power stage makes use of a travelling-wave amplifier. Wide use is made of precision high-frequency ferrite components. The microwave power generator is based on a 50 mW transmit oscillator and 2 mW receive oscillator, both operating in the range of 46-51 Mc/s; a chain of multipliers brings the frequency into the required range of 5875-6475 Mc/s, with a stability of ± 15 ppm. The receiving IF amplifier can provide as much as 60 dB gain and includes a regulating stage for automatic gain control; wide-band operation is made possible by the use of planar epitaxial transistors having a cut-off frequency of up to 1000 Mc/s. Cassegrain-type aerial with a diameter of 4m provides an efficiency of over 60%. An auxiliary radio relay system, operating in the same frequency range but independent of the main system, is provided for the purposes of remote control and supervision.