A Novel Configuration for Microwave Resonator with Zero Temperature-Coefficient

We present a simple yet novel design of a cylindrical microwave resonator with a turnover in the frequency versus temperature response. The basis for the design is to compensate for the thermal changes in the radius and length of the cavity cylinder by using re-entrant end caps with a higher temperature coefficient of expansion than that of the cylinder. For the proper choice of inside cylinder diameter and length, one can achieve sufficient separation of the desired TE023 mode from competing modes, Q-factors approaching 59,000, and a turnover temperature at the desired frequency. Details of a X-band cavity using silver plated molybdenum for the cylinder and silver plated aluminum for the re-entrant end caps are presented .