Surface Micromachined Integrable High Efficiency Ridge Gap Waveguide Bandpass Filter for G-Band 6G Applications

This paper presents a third-order band pass filter (BPF) ridge gap waveguide (RGWG) fabricated utilizing the combination of SU-8 polymer and a photolithography and subsequent metallization process. The RGWG device is designed, simulated, and fabricated to operate in the G-band (110 - 300 GHz) frequency range. With a center frequency of 167 GHz, the fabricated devices have average surface roughness and fabrication tolerances less than 100 nm and
$\mathbf{25} \boldsymbol{\mu} \mathbf{m}$
in all three dimensions, respectively, which are significantly smaller than those of computer numerically controlled (CNC) fabricated devices, e.g. greater than 300nm and
$\mathbf{50}\ \ \boldsymbol{\mu} \mathbf{m}$
respectively. The micromachined SU-8 based devices in simulation show 0.87 dB insertion loss at a center frequency of 167 GHz with a 7.5% fractional bandwidth (FBW). Realized the BPF-RGWG device has potential for use in high-frequency applications such as satellite communication and millimeter-wave imaging systems.