Novel Multiple-Band Filter Using Mixed Cavity Resonator and Dielectric Resonator

In this article, a quintuple-band bandpass filter is proposed by using a mixed-mode resonator composed of two dielectric resonant modes and three cavity modes. The electric field of the cavity mode TE101, instead of the widely used metal probe, is used to excite the TE01δ-mode dielectric resonator (DR). Besides, several DRs inside the cavity can be simultaneously excited by this unidirectional electric field without requiring extra feeding structure. Then, two TE01δ-mode DRs with different resonant frequencies are inserted into a triple-mode cavity resonator under the operation of resonant modes TE101, TE011, and TM110, thus forming a quintuple-mode resonator. Then, this mixed-mode resonator is used to realize the quintuple-band bandpass filter, and a second-order quintuple-band bandpass filter is designed and fabricated to validate the proposed design concept.