New design of ultra-wideband bandpass filter using metamaterial resonator

An ultra-wideband (UWB) bandpass filter based on composite right/left handed (CRLH) transmission line is presented in this paper. The bandwidth of the filter can be widen by the high-low-high step-impedance section and two novel interdigital capacitors of the CRLH transmission line. The common short circuited inductive stub of two capacitors exhibits stopband rejection level greater than 30 dB at both the lower and upper band edges. Numerical simulations using ANSYS HFSS reveal 3-dB bandwidth of 7.5 GHz from 3.1 GHz to 10.6 GHz and the average insertion loss of 0.5 dB while the return loss of more than 18 dB in passband. In addition, a DGS structure is proposed to create a notched band in order to attenuate some undesired signals such as local area networks (WLAN) in the UWB band. The proposed filter will be useful in the wireless communication systems.