Low Pass Filter Design with CSRR as Defected Ground Structure

Abstract

This paper presents the design of a low pass filter using complementary square split ring resonator (CSRR) used as defected ground structure (DGS) below a simple transmission line. The design starts with the popular square split ring resonator (SRR) and develops the dual split ring structure which tunes an octave above the resonant frequency. The complementary structure is used as a defected ground structure below a transmission line to design a low pass filter (LPF) with a cut-off at 2.54 GHz. Microstrip filter design is not used in the model but purely tuned with the CSRR structure. The design is verified with its current distribution studied both at pass band and stop band. The design has various potential applications in microwave systems and circuits where these tuning structures can be implemented below the transmission line as a filter on the ground plane along with amplifiers, couplers, attenuators and switches. The effect of metal enclosure around the filter for EMI shielding is simulated for practical implementation of these filter along with other microwave systems.