Microwave Power Up-Converters for Angle Modulated Signals using Phase-Locked Microwave Oscillators

A new technique of microwave power generation using the phase-locked loop principle is described. It combines the functions of a microwave up-converter and a microwave power amplifier and is therefore particularly attractive for heterodyne-type radio relay transmitters. Power up-conversion is accomplished by phase-locking the output signal of a voltage-controlled microwave power oscillator to the angle-modulated i.f. signal. The phase comparison is done at the intermediate frequency with a down-converted sample of the VCO signal. A theoretical analysis and experimental results with transistor and GUNN-VCOs indicate an overall transmitter performance comparable to that obtained with a conventional up-converter-amplifier configuration with the advantage of much less complex microwave circuitry.