A 94-GHz overmoded waveguide oscillator with Gunn diodes

Spatial power combining of Gunn diodes with an efficiency of more than 80 % has been demonstrated at W-band using an overmoded waveguide resonator with an array of TE,,mode waveguides. This resonator makes use of selective coupling between an mxn TE10 modes in the waveguide Gunn diode array and the TEm0 mode in the overmoded waveguide to produce high power. An efficiency of 84 % and an output power of about 0.23 W at 94 GHz, has been achieved using three Gunn diodes. The output mode of TE30 in the oscillator has been converted to the fundamental TE10 mode with an efficiency of about 80 % using an oversized waveguide with an H-corner.