A Miniaturized Wideband Half Mode Substrate Integrated Waveguide Bandpass Filter for C Band Applications

We propose a novel compact wideband bandpass filter for C band applications. The bandpass filter is designed using half mode substrate integrated waveguide and defected ground structure in the form of periodic circular vias are incorporated into it. RT/Duroid 5880 with a permittivity of 2.2 and thickness of 0.508 mm is used as substrate for designing the proposed bandpass filter. Detailed parametric analysis is presented to study the influence of various design parameters on the filter characteristics. The proposed filter exhibits a passband over 5.7-7.3 GHz with
$\vert\mathrm{S}_{11}\vert <-10\text{dB}$
and
$\vert\mathrm{S}_{21}\vert \approx -0.6\text{dB}$
. In addition, the filter has a 3 dB fractional bandwidth of 23.2% along with a small size of 0.015 Ai. The proposed bandpass filter has higher 3dB bandwidth and a much smaller size as compared to the state-of-the-art designs.