Resonator and Preselector in Balanced Strip Line

One of Raytheon's commercial applications involves microwave circuitry in balanced strip line, with a 3/8" spacing between ground planes. Though the less critical parts of the unit are etched in copper-clad Teflon-Fibreglas, two of the components are of higher Q than can reliably be obtained in the presence of plastic. They are: 1. a resonator, for use as a frequency stabilizing reference element in an AFC circuit; and 2. a four-stage maximally flat preselector filter. These units are made of separate strips of metal, and do not depend on the plastic sheet for their support.