Compact lowpass filter with wide stop-band using coupled-line hairpin unit

Abstract

A novel transmission line configuration is proposed to design a lowpass filter (LPF) with sharp cutoff frequency response and wide rejection bandwidth. The proposed LPF is realised by a cascading microstrip coupled-line hairpin unit, semi-circle defected ground structures and semi-circle stepped-impedance shunt stubs. Theoretical and simulated results are presented, which are in good agreement with measured results.