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Abstract

In this paper, a novel miniaturized broadband dielectric waveguide (DW) bandpass filter (BPF) with wide stopband response is proposed. The proposed BPF is composed of two square DW resonators operating in TM₁₀₁ mode. By etching a coplanar waveguide (CPW) resonator on a silver-plated metal surface in the middle of the two DW resonators, an additional resonant mode is introduced, thereby broadening the bandwidth of the filter while retaining the inherent advantages of the DW structure. Simultaneously, the CPW resonator creates a new coupling path that enables cross-coupling and introduces a controlled transmission zero (TZ). The position of the TZ can be adjusted to suppress the second harmonic of the filter, ensuring effective stopband performance. For verification, a DW BPF with center frequency of 5 GHz and a fractional bandwidth of 11.4% was designed, fabricated, and measured. The measured results are in excellent agreement with the simulated ones. Specifically, the upper stopband of the filter extends to twice of the center frequency (10 GHz), demonstrating the wide stopband characteristics of the filter.

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doi:10.2528/PIERC24122403

Dr. Chuanyun Wang

Mr. Hao Huang

Dr. Pin Wen