Gunn effect oscillator modules using microstrip circuits

Microwave oscillator modules for operation at X and S-band have been designed which use Gunn devices as the rf power source. More than 10 mW CW at X-band and 20 watts pulsed at S-band has been obtained. The microstrip circuit, together with the necessary filters and blocking capacitor, is produced on an alumina substrate in a single operation using photolithographic techniques. Electronic tuning is achieved by the incorporation of a series mounted varactor diode. Microstrip circulators have been developed for use in both TR and injection locking applications. The design of the circuit elements and their combination to achieve the optimum output power and tuning range is discussed. The injection locking characteristic and the variation of frequency and output power with temperature are described.