Novel Balanced Single/Dual-band Bandpass Filters Based on Circular Patch Resonator

TL;DR

This paper introduces a novel design method for single and dual-band balanced bandpass filters using circular patch resonators, achieving high common-mode suppression and improved performance through innovative perturbations.

Contribution

It presents a new approach to design balanced BPFs with enhanced suppression and tunability by modifying the circular patch resonator and incorporating perturbation techniques.

Findings

High common-mode suppression achieved in passbands

Good agreement between simulated and measured results

Effective dual-band filter performance demonstrated

Abstract

A new approach for designing the single-band and dual-band balanced bandpass filters (BPFs) based on the circular patch resonator is proposed in this work. By modifying the output balanced ports of the balanced BPFs to inhibit or transport TM31 mode of the circular patch resonator under the differential-mode (DM) excitation, a single-band or dual-band balanced BPF can realized. As the odd modes could be restrained under the common-mode (CM) excitation, the balanced BPFs could achieve high CM suppression in the DM passbands. Meanwhile, several perturbing ways are introduced to improve the performance of the balanced BPFs. Specifically, perturbation vias are introduced to disturb the electric field distribution to improve the CM suppression in the DM passbands, and slots are cut on the circular patch resonators to perturb the current distribution to modify the second DM passband of the dual-band balanced BPF. Furthermore, the proposed single-band and dual-band balanced BPFs are fabricated and characterized. Good agreement can be achieved between the simulated and measured results of the fabricated balanced BPFs, which validates the feasibility of the proposed design method.