AN OPEN RESONATOR LOADED WITH A RECTANGULAR WAVEGUIDE SECTION

Abstract

A hemispherical open resonator with a rectangular waveguide section mounted at the center of the open resonator plane mirror is considered. A theoretical analysis has been made to find out that the excitation efficiency of the waveguide wave TE10 excited by the open resonator oscillation TEM00q can reach 90 % for some certain cross-sectional dimensions of the waveguide. To this end, a hemispherical open resonator with a superdimensional rectangular waveguide section was experimentally studied in the 4 mm wave region. The cross-sectional dimensions were chosen under the condition of obtaining maximum excitation efficiency of the fundamental waveguide wave. The study shows that the excitation of the fundamental mode alone holds in this resonant system across the whole tuning range. Comparison of reflection coefficients of a waveguide-loaded resonator either with or without a reflecting diffraction grating at the waveguide section bottom indicates that both of the electrodynamic systems have nearly equal losses.

Keywords

• excitation efficiency
• open resonator
• overmoded rectangular waveguide
• diffraction grating