Abstract: A vacuum variable capacitor includes a vacuum bellows for allowing a pressure differential between two volumes inside the capacitor, wherein one of the volumes may be a vacuum volume. The vacuum variable capacitor further includes a conductive bellows disposed within the vacuum volume. In such an arrangement, the materials selected for the vacuum bellows and the conductive bellows may be selected to optimize the function of each bellows.

Abstract: A tuning head for use with a variable capacitor includes a coupler having a gap, a first optical fiber operatively coupled to the coupler, and a second optical fiber operatively coupled to the coupler. The first and second optical fibers are optically coupled across the gap when the gap is not obstructed. The tuning head further includes an obstruction member that is movable with respect to the coupler and is adapted to fit within the gap to selectively obstruct said optical coupling of said first and second optical fibers. A movement mechanism is also provided to create relative motion between said obstruction member and said coupler.