Miniaturized Hybrid Filter Using Stripline and LC-Loaded SIW Resonators

In this study, a miniaturized hybrid filter based on substrate integrated waveguide (SIW) technology with a wide upper stopband and skirt characteristics is presented and analyzed. A third-order highly selective hybrid filter has been implemented, fabricated, and measured by combining two LC resonators and a stripline resonator in closed cavities without extra radiation loss. Good agreement between the EM simulated data and the measured result is observed. The filter exhibits an electrical size of 0.44 ${\lambda }_{0}\times \,\,0.64\,\,\lambda _{0}$ only. The measured in-band minimum insertion loss is around 0.9 dB, and a high stopband rejection up to 2.25 $f_{0}$ ( $f_{0}=10$ GHz) is achieved.