New Elements for Coupling of the High-Quality Millimeter-Wave Resonators with Waveguides: Theory, Design, Experiment

Techniques for electrodynamic-level calculation of slot-grating wideband coupling elements for single- mode waveguides are developed. New coupling devices that ensure the obtaining of a voltage standing-wave ratio of 1.6 in the entire tuning range of resonator without readjustment of the coupling devices in resonators do not deteriorate the loaded Q factor of the resonator. A numerical technique for electromagnetic modelling of the element for coupling of high-quality resonators with single mode waveguides is considered. For broadband matching a smooth waveguide transition ending with a narrow slit has been suggested. It was shown that such a coupling element allows an open resonators as well as corrugated ones to be realized that is readjustable in a wide range from 8 to 1 millimeter and retains good matching standing-wave ratio < 1.7 with the waveguide without any coupling adjustment in the for-reflection scheme.