A broad-bandwidth dual-band bandpass filter design using composite right/left handed transmission lines

In this paper, a novel design of a dual-band bandpass filter (BPF) with a broad bandwidth and low insertion loss is presented. The proposed BPF consists of short-stub composite right/left handed transmission lines and dual-band admittance inverters. Both theory and experiment have been presented in order to validate the proposed structure. The proposed dual-band BPF has the 3-dB fractional bandwidths (FBWs) of 50.24% and 20.20% at center frequencies of 2.40 GHz and 5.20 GHz, respectively, useful for wireless local area networks applications. From the measured performance, the dual-band BPF has the low insertion losses of 0.28 dB and 0.46 dB for each passband and high isolation of 39.9 dB in between two passbands.