UWB bandpass filter using complementary split-ring resonator-based highpass filter and defected ground structure

A compact planar microstrip ultra-wideband (UWB) bandpass filter is presented. The proposed UWB filter is realised by cascading a highpass filter (HPF) and a lowpass filter (LPF). The HPF consists of complementary split-ring resonator (CSRR) with dual C-shaped couplings. The LPF is achieved by a hybrid microstrip and four backside corrugated slots etched on ground plane. Combining these two structures, a new UWB bandpass filter is obtained. Simulated and measured results show that the proposed bandpass filter has a wide bandwidth from 3.0 to 10.7 GHz, and insertion loss is less than 2.0 dB over the whole pass band. It also achieves a wide stop band with 30 dB attenuation up to 18 GHz.