Suggestions for finding optimum materials and manufacturing methods for metallic microwave cavity resonators

The selection and combination of appropriate materials and manufacturing methods for metrology-grade microwave resonators can be improved by tuned design methodology and manufacturability analysis which will enhance performance and long-term reliability and are often able to reduce cost as well. Typical interest areas include steel resonators both for Cs- or H-maser atomic standards and those operating as stand-alone devices in the millimeter region. New performance levels are feasible due to improved surface quality, stability, and the reduction of seam widths by e.g. laser processing. A stepwise procedure points out solutions particularly for e.g. challenging airborne, sea or space platforms in the higher microwave bands where prototype specifications exceeding those of conventional copper cavities have been achieved. The loaded quality factor of a 15 GHz rectangular steel cavity approaches 400 in a 50 ohm system with a simultaneous tuning error below 0.1 MHz seeming feasible.