Compact Triple-Mode Bandpass Filter Using a Cylindrical Dielectric Resonator

Abstract

In this paper, the design of a compact triple-mode bandpass filter using a high-Q cylindrical dielectric resonator is proposed. In detail, the triple TE01δ modes along three orthogonal axes are used and novel coupling structure in the metallic enclosure is adopted to introduce the coupling between the resonant modes. Due to the cross coupling, the proposed bandpass filter has an asymmetric frequency response with flexible three transmission zeros, one of which can be located very close to the passband edge to provide an extremely sharp skirt characteristic with low insertion loss. The proposed filter is about 60 % miniaturized compared with conventional single-mode dielectric resonator filter. The proposed bandpass filter design is validated by the circuit and 3D EM simulations and measurements compared to the target specifications.