Bandstop Filter based on Complementary Split Ring Resonators Defected Microstrip Structure

Abstract

Novel bandstop filters based on the defected microstrip structure with complementary split-ring resonators (CSRRs)/half-CSRRs etched on the microstrip surface are presented in this paper. By changing the configurations of the CSRRs, varied stop-band and pass-band characteristics are observed, and half-CSRRs is proposed to build a novel bandstop filter. A detailed explanation for the generation and variations of the stop-band and pass-band has been given. Lumped equivalent circuit analysis model is developed as well. The proposed filters exhibit compact size due to the employment of sub-wavelength resonators, and the overall size of the prototype is 12.2 mm × 28.95 mm × 0.8 mm. The measured −20 dB bandwidth of S ₂₁ is from 2.51 GHz to 3 GHz, and the S ₂₁ exhibits a wide spurious free response up to 10 GHz.