Active Quasi-Optical Cavity Resonators Similar to Sinai and Bunimovich Billiards as Self-Excited Millimeter Wave System

The goal of the paper is to study experimentally the auto-oscillating systems based on quasi-optical 3D cavity resonators similar to instable Bunimovich and Sinai billiards and to detect the microwave generation in such systems activated by a Gunn diode. The concept of using this unstable resonator as a part of an active oscillating system is based on the following. The high quality factor resonator serves as an oscillating system in microwave oscillators. An increase of the quality factor of an oscillatory circuit leads to the reduction of excitation threshold of the oscillator and the increase of its frequency stability.