Triple-Mode Bandpass Filter Based on TM Dielectric Rod Resonators

In this paper, a new triple-mode resonator structure which is based on TM mode operation in dielectric rods is presented. Due to the specific arrangement of the dielectric rods on a metallic core, three new fundamental eigenmode resonances exist at the same frequency. Compared to previous works based on TM triple-mode resonators, the new structure requires a minimum number of dielectric rods. By using dielectric rods, a simple construction of a triple-mode filter is possible without the need of complex customized dielectric resonator structures. This is shown by a manufactured prototype. A suitable filter topology is derived by simulated investigations.