Study of a quasi-optic oscillator

Abstract

This thesis is concerned with an experimental study of a novel microwave oscillator which is based on quasi-optic principles rather than more conventional closed cavity techniques. A quasi-optic open cavity resonator is used in order to combine and stabilize the frequency of many solid state source modules. At mm wavelengths, the small physical size of the open resonator, (127 mm diameter mirrors at Q-band) enables the fabrication of medium power oscillators with dimensions suitable for integration within a practical system. A self-oscillating microstrip patch antenna, mounted conformally with the resonator mirror surface, is developed as the basic source module. A suitable method of coupling many of these modules efficiently to a beam mode supported by the open resonator is discussed, together with the dependence of the preferred active cavity mode upon the array geometry. Initial experimental investigations have been undertaken at J-Band (12-18 GHz) yielding techniques that have been successfully applied at Q-Band (26 - 40 GHz).