Capacitor arrangements, especially for an electronically tunable band

Abstract

A capacitor arrangement which is especially suited for use in an electronically tunable narrow band tuned cavity filter includes two capacitor plate portions which are juxtaposed one another to form a capacitor. One of the capacitor plate portions may be provided with a recess and with an internally threaded bore which opens into the recess, and an externally threaded trimmer slug may be received in the bore and extend to a greater or lesser degree into the recess and thus to contribute to a greater or lesser degree to the total capacitance of the capacitor. A dielectric spacer may be interposed between the capacitor plate portions to determine the size of the gap therebetween and to maintain the gap size constant. One of the capacitor plate portions may be mounted on a support for movement toward and away from the other capacitor plate portion and be urged toward the latter in a yieldable manner so as to avoid undue stressing of the dielectric spacer resulting either from vibrations or from thermal expansion. When the capacitor arrangement is to be used in a tuned cavity filter including a plurality of resonator bars which are mounted in a cantilevered fashion, a portion of the respective resonator bar may be used as one of the capacitor plate portions, and a set of the capacitor arrangements of this construction may be arranged around the respective resonator bar so as to suppress oscillations of the latter in all transverse directions.