Design and Realization of Bent Y-Shaped Ceramic Dual-Mode Resonators and Filters

In this paper, the design and realization of second-and fourth order bent Y-shaped ceramic dual-mode resonators and filters is discussed. The resonators are based on uniform cylindrical ceramic TM mode rods, which are connected to a metal core. This approach allows the cost-efficient realization of complex shaped dual-mode resonators. The filters are designed to use a pair of degenerated TM modes, which can be divided into a mode with electric as well as a mode with magnetic symmetry plane. Each dual-mode resonator contributes two resonances as well as one transmission zero (TZ) to the filter response. By varying the angles between the ceramic rods, it is shown that the filter parameters can be adjusted. Due to the TM mode operation, a proper contact between the ceramic rods and the metallic housing is required. Two different solutions are proposed in this paper: On the one hand, the cavity is made from a copper sheet. This approach enables the possibility that the ceramic resonators are soldered with the surrounding housing. On the other hand, threads are soldered to the ceramics, with which the ceramic core can be screwed to the housing. Second- and fourth order filters are manufactured as proof of concept.