Work

Inline Waveguide Filters With Transmission Zeros Using Frequency-Variant Couplings

Year: 2025

Type: article

Abstract: This article introduces a novel frequency-variant coupling structure with high adjustability for waveguide filters. Although this structure is proposed for rectangular cavities, the same principle can be applied to other cavity geometries. The proposed structure is compatible with standard micromachining technologies. Using this coupling structure, two inline Nth-order waveguide filters with$N-1$and$N+1$transmission zeros (TZs) are developed. A fourth-order bandpass filter (BPF) with three TZs at 245, 285, and 288 GHz is designed, operating at a center frequency of 270 GHz with a 2% fractional bandwidth. In addition, a second-order BPF with a center frequency of 280 GHz and a 0.71% fractional bandwidth, utilizing three TZs at 230, 300, and 308 GHz, is also developed. Prototypes of both filters are fabricated using silicon micromachining. The measured insertion loss and return loss (RL) in the passband are 2 dB and better than 18 dB, respectively, for the fourth-order filter and 2.1 dB and better than 11 dB for the second-order filter, respectively.

Source: IEEE Transactions on Microwave Theory and Techniques

DOI: 10.1109/tmtt.2025.3541149

Authors: Mohammad Mehrabi Gohari, Oleksandr Glubokov, Joachim Oberhammer

Institution: KTH Royal Institute of Technology

Language: English

Topic: Microwave Engineering and Waveguides

Subfield: Electrical and Electronic Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $2,645

Funders: Vetenskapsrådet, Hellenic Foundation for Research and Innovation