Design of Series Feedback Millimeter Wave Oscillators employing Whispering Gallery Mode Dielectric Resonators

Design and performance of millimeter wave oscillators at 36.5 GHz and 44.5 GHz employing Whispering Gallery Mode Dielectric Resonators (WGMDR) and commercially available HEMTs are presented. A special microstrip coupling circuit has been developed for the WGMDR. This coupling avoids the mode splitting of the degenerate Whispering Gallery Modes and also avoids out of band instabilities in a series feedback oscillator. Two oscillators at 36.5GHz employing a WGE7,0,0 mode resonator and at 44.5 GHz employing a WGE9,0,0 mode resonator have been designed. High output power(> 7dBm) and efficiency (10%) have been achieved for both oscillators.