In this paper, the characteristics of novel modified composite right/left-handed (CRLH) transmission lines are discussed, and an ultra-wideband (UWB) bandpass filter (BPF) using the modified CRLH transmission lines is presented. Design formulas of a novel modified CRLH unit cell are theoretically derived. Based on the design formulas, the UWB bandpass filter with three unit cells is designed, fabricated, and measured. The measurement results show that the UWB bandpass filter has an insertion loss of less than 1 dB, bandwidths of 2.9~4.9 GHz, and a rejection of greater than 50 dB at 5.8 GHz.
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