Spatial power combining of second-harmonic Gunn diodes using an overmoded-waveguide resonator at W-band

Efficient power combining of second-harmonic Gunn diodes using an overmoded waveguide resonator has been demonstrated at W-band. In the resonator, a Gunn diode array oscillates at a fundamental frequency and then generates harmonic waves in the common overmoded waveguide resonator. A lamellar backshort has been used to adjust separately the oscillation frequency and the output power. As based on theoretical analyses, the resonator configuration including an output coupling has been optimized. As a result, a combining efficiency of 67% and an output power of 140 mW at 97 GHz have been achieved with three Gunn diodes. The output frequency has been changed from 89.3GHz to 99GHz using the lamellar backshort.