Schottky Barrier Receiver Modulator

The receiver modulator of the TD-3 repeater is the first unit in the signal path which uses active devices. Because it is in the signal path, its transmission characteristics must be well behaved, and because it is at the front end of the repeater, its low thermal noise is of considerable importance to the performance of the system. 2.1 Objectives The objective of the development was to obtain a solid state downconverter-preamplifier for the microwave receiver of the TD-3 system. The unit had to be reliable, inexpensive, and in a shape to ease the transmitter-receiver bay designing. It should be easy to manufacture and maintain, and should have a minimum of adjustments. It should be designed to last at least 20 years and be rugged enough to withstand the shock and temperature extremes of shipment. In addition, it should conform to the following electrical specifications: Signal midband frequency: fSI = 3710, 3730, . . . 4190 MHz, according to the frequency plan discussed in Ref. 1. Local oscillator frequency: fL0 = 3780, 3800, . . . 4120 MHz, according to the frequency plan discussed in Ref. 1. 1257