Schimmel, Jörn; Numssen, Kai (Spinner GmbH, Aiblinger Strasse 30, 83620 Westerham, Germany)
Not reaching the theoretical quality factors of cavity filters is an area for concern in the development of cavity resonator filters in sheet techniques. Apart from obvious losses caused by surface currents possible lossy structures are tuning screws and soldered joints. At present, however, there is no method to quantify the contributions of those to the overall losses. This paper addresses the question how to determine losses due to various types of joints often used in radiofrequency design and introduces an appropriate measurement technique to characterize contact resistances. Furthermore the mathematical approach how to define and determine a comparable value is presented. The filter developer can take the given information into account to optimize filter structures.