The TH-3 Microwave Radio Transmitter-Receiver

A new transmitter-receiver for use in 6-GHz microwave radio relay systems is described. Utilizing all solid-state devices except for the output amplifier (traveling-wave tube), the noise objective is 11,000 pW (psophometric) for a message load of 1800 circuits for a 4000-mile system. The system was designed to use many components and associated auxiliary systems in common with the new 4-GHz solid-state TD-3 system, to provide an integrated 4/6-GHz microwave radio facility. New techniques used in the design are microwave integrated circuits, microwave directional filters, microwave delay equalization, RF squelch, and unbalanced modulators. Some performance data on early models are given.