A Compact Ultra-Wideband Bandpass Filter With Sharp-Rejection Using Complementary Split Ring Resonators

A compact and sharp-rejection ultra-wideband (uwb) microstrip bandpass filter (bpf) is developed using of left handed metamaterials realized by complementary split ring resonator (csrr). moreover, proposed structure consists of two doublets parallel coupling gaps at each side of a microstrip ring. this structure shows a significantly wider passband due to the introduction of a cross-coupling between the feed lines (input and output) which generate four pairs of attenuation poles in the passband. also, using two csrrs etched in the ground plane, and series gap inside the microstrip ring leads to the addition of two extra transmission poles at the lower and upper edges of the filter. consequently, a compact six-pole ultra-wide bandpass filter is designed which exhibits extremely sharp rejection skirts around the target passband .the proposed filter has a passband covers 3.4 to 10.15 ghz and its measured 3 db fractional bandwidth is about 100%. furthermore, rejection level better than 20 db in upper stopband is extended to around 14.7 ghz both in simulation and measurement. experimental verification is provided and good agreement has been found between simulation and measurement. the total size of the proposed uwb filter is more compact compared with known similar filters