Miniaturized Hybrid Filter Using Stripline and LC-Loaded SIW Resonators

Abstract

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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\lambda }_{0}\times \,\,0.64\,\,\lambda _{0}$ </tex-math></inline-formula> only. The measured in-band minimum insertion loss is around 0.9 dB, and a high stopband rejection up to 2.25 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$f_{0}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$f_{0}=10$ </tex-math></inline-formula> GHz) is achieved.