Design and characterisation of HE₁₁ dual-mode dielectric-loaded filter for cellular base station applications

Abstract

This paper presents a HE11 dual-mode dielectric-loaded bandpass filter for cellular base station applications. The filter consists of a ceramic puck that is placed centrally on the base of a metallic housing. The resonator offers a size reduction ratio of approximately 7:1 compared with equivalent air-filled coaxial filters. The filter is designed at a resonant frequency of 2.05 GHz and bandwidth of 50 MHz. The spurious-free window (SFW) was 500 MHz from the fundamental frequency. A fourth order dual-mode bandpass filter is designed, fabricated, and tested to validate the proposed approach. A good agreement between the measurement and simulation results is demonstrated.