Radiation efficiency in planar quasioptical grid oscillators

Abstract

In order to produce moderate power ai millimeter-wave frequencies, the output powers of many solid-state dec ices are combined quasioptically in order to eliminate losses attached to waveguide-type combiners. A planar quasioptical grid oscillator is one such scheme. The planar quasioptical grid oscillators consist of arbitrary periodic metal gratings printed on dielectric substrate and loaded with FETs. However. if the design of gratings is not proper, the advantage gained due to the elimination of losses in the waveguide is offset by the decreased radiation efficiency due to the power getting coupled to substrate-mode excitation. In this letter, the MOM and Galerkin's analysis are used to study the radiation efficiency of planar quasioptical grids. (C) 2000 , Inc.