A D-Band Substrate Integrated Waveguide Bandpass Filter Based on Silicon Carbide Technology

In this paper, a third-order bandpass filter (BPF) operating at D-band (110–170 GHz) based on substrate integrated waveguide (SIW) technology is designed on a
$100-\text{um}$
-thick silicon carbide (SiC) substrate. The passband is constructed by two TE
101
mode-based SIW rectangular cavities (cavity 1 and 3) coupled with a TE
103
mode-based over-moded SIW rectangular cavity (cavity 2). With cavity 2 is arranged adwisely and operated with TE
103
mode, a larger resonant cavity size denotes a bigger coupling window size could be realized between cavity 2 and the other cavities, thus enabling the designed BPF to perform with a wider bandwidth and a higher unloaded quality factor. Moreover, thanks to the cross coupling generated between two TE
101
mode-based SIW resonant cavities, a transmission zero (TZ) is successfully produced at the upper stopband that improving the frequency-selectivity. The finite-element full-wave electromagnetic software is utilized to simulate the designed BPF. To validate the design, a BPF is designed and simulated with a passband operating at 140 GHz, featuring a 9% 3-dB fractional bandwidth (FBW), a 1.04 dB insert loss (IL), and a 20 dB return loss (RL), and the synthesized responses are found to be in good agreement with the simulated characteristics. These results demonstrate the exceptional performance of SiC-based SIW filters and highlight the promising potential of SIWs in the design of filters, antennas, and other circuit elements on SiC-based chips.