A Fabry-Perot resonator with a grooved mirror (Fig. 1) has been used for coherent powercombining of active elements in the millimetre and submillimeter wave region. The elements aremounted on the mirror which acts as an impedance matching circuit as well as a heat sink, promising ahigh power operation of the elements. In this paper, equivalent circuits of the resonator with two- terminal (Gunn diodes) and three-terminal (HEMT's) elements are presented.
"Design of a millimeter wave quasi-optical oscillator", Proc. SPIE 2104, 18th International Conference on Infrared and Millimeter Waves, 21046P (30 August 1993); doi: 10.1117/12.2298673; https://doi.org/10.1117/12.2298673