Miniaturized bandpass filter using dual-mode hexagonal loop resonator

Abstract

A novel miniaturized dual-mode bandpass filter (BPF) using hexagonal loop resonator is presented. In order to reduce the circuit size, capacitive loading structure is applied to enhance the self-capacitance and electrical length of the hexagonal loop resonator. The frequency selectivity and out-of-band rejection of the proposed BPF can be improved by the two inherent transmission zeros in each side of the passband. Compared with the conventional hexagonal loop resonator without capacitive loading structure, the size of the proposed resonator is reduced by 46.6%. The simulated and measured results are presented and show good agreement.