Compact Quad-Band bandpass Filter Based on Complementary Split Ring Resonators as DGS

In this paper, a compact quad-band bandpass filter based on complement square split-ring resonator (CSRR) defected ground structure (DGS) is proposed. The CSRR as DGS can generate two passbands. Two transmission zeros are created to improve the selectivity of the proposed passband filter and isolation between the generated passbands. Design is simulated using ADS/Momentum and EM Simulation software (CST). The simulated results show that the proposed quad-band BPF has four passbands centered at 1.96, 3.19, 4.69 and 6.43 GHz with the fractional bandwidth of 17.85, 9.4, 11.96 and 23.29%, respectively. The simulated ILs at CF of each passband are 1.23, 2.25, 1.74, and 1.54 dB, respectively.