Ridge Gap Waveguide Low Pass Filters: A Systematic Design Approach

In satellite communication systems, Low Pass Filters (LPFs) are used to remove harmonics generated from the power source, minimize interference, and enhance the signal-to-noise ratio. Through the filter design process, various aspects must be considered such as the insertion loss, bandwidth, weight, and size. A stepped Impedance filter is a typical topology to realize the LPFs. The stepped impedance filter design process goes through multiple design steps starting from the normalized prototype design and ending with the realization of the filter sections. The filter realization significantly depends on the host guiding structure. This paper, presents, for the first time, a systematic design approach for the stepped impedance filter based on ridge gap waveguide technology. An accurate mathematical model for calculating a virtual cutoff for the ridge gap waveguide is introduced, which is deployed in the proposed design methodology. Moreover, a prototype of the stepped impedance filter is fabricated and measured, with measured results closely aligning with simulations.