A novel design of a compact miniature microstrip low pass filter based on SRR

Abstract

In this work, a novel compact microstrip low-pass filter is designed based on square split ring resonator. The SRR is used to reduce the size of the filter and to improve the good electrical performances. The dumbbell-shaped defected ground structure is introduced into the ground plane in order to achieve a desired cutoff frequency of 1.2 GHz with a ripple level less than 0.2 dB in the pass-band and an attenuation better than 20 dB in the rejected band. The proposed filter is designed on an FR-4 substrate having a thickness of 1.6mm, a dielectric constant of 4.4 and loss tangent of 0.025. The whole area of the proposed circuit is 24×26mm2. The computed results obtained by CST microwave and Ansoft HFSS are in good agreement. The size of LPF is miniaturized by 60% compared to the conventional filter.