Contact-less capacitive tuner for microwave comb-line mechanically-tuned filter

The paper presents an approach to avoiding the problem of obtaining the electrical contact in typical tuners for stripline-based combline filters. The tuner structure shown here does not require any electrical contact and is based on the concept of the cylindrical capacitor with a sliding inner part. The idea of the construction and working principle are shown together with a simulation and measurement results for a manufactured model of 5^th order combline L-band filter.