Design of a novel microstrip lowpass filter for UWB chipless RFID readers

UWB chipless RFID receivers require compact and low cost integration solutions aiming at improving the signal integrity. A wide stopband, high selectivity and compact microstrip lowpass filter (LPF) is therefore needed. A combination of compact microstrip resonant cells (CMRCs) and uniquely shaped defect ground structures (DGS) are used in present LPF design to optimize the filter performances. The stopband with an attenuation level lower than 20 dB is obtained from 3.1 GHz up to 20 GHz. Both simulated and measured results are presented, showing a good agreement between simulation and measurement.