Compact Dual-Mode Wideband Filter Based on Complementary Split-Ring Resonator

This letter proposes a microstrip filter based on a dual-mode complementary split-ring resonator (DMCSRR). For the input/output coupling, a dual C-shaped feed structure is implemented together with the DMCSRR to acheive a wideband response. The resonator offers a wide fractional bandwidth of 62% at the central frequency of 2.23 GHz and a very compact structure with a footprint of 0.0625λ
_g
×0.18λ
_g
, where λ
_g
is the guided wavelength at the midband frequency. A comprehensive lumped element circuit analysis accompanies the simulation and measurement results.