Compact UWB band-pass filter utilizing modified composite right/left-handed structure with cross coupling

Abstract

An ultra wide band (UWB) band-pass filter (BPF) utilizing one modified composite-right/left-handed (CRLH) unit cell is proposed. By introducing the capacitive cross coupling to the traditional CRLH structure, the phase shift in the right-handed pass- band can be controlled, meanwhile, the cross coupling has negligible effect on the left-handed pass-band. The appropriate cross coupling can create three controllable transmission zeros. Thus, an UWB BPF with high selectivity is developed using only one unit cell, which leads to low insertion loss (less than 1.35dB) and compact size (0.47λ0×0.28λ0). The fabricated filter exhibits a rejection level higher than 20dB at the stop-band from 11.95-16GHz and flat group delay across the pass-band.