a simple uwb microstrip band-pass filter with an ultra-wide stopband using parallel coupled lines and hairpin resonators

In this paper a simple ultra-wide band (uwb) microstrip band pass filter (bpf) with an ultra-wide stopband using novel dual hairpin resonators and parallel-coupled lines is proposed. the proposed filter has a wide pass band of 3.1 to 10.2 ghz with only 0.1 db insertion loss. this wide pass band of 7.1 ghz, shows 106.7% fractional band width (fbw). the proposed bpf not only correctly operates at the ultra-wide pass band, but also provides an ultra-wide stopband from 12.8 to 28.2 ghz with more than 20 db attenuation level. the proposed bpf has a very simple structure, which consists of four novel hairpin resonators and simple parallel-coupled lines. the proposed bpf has a compact size, which the overall circuit size of the device is only 11.7 mm × 7.2 mm (0.35 λ × 0.22 λ), where λ, is calculated at the center frequency of 6.65 ghz. the proposed device is simulated, fabricated and tested. the measured results confirm the correct performance of the proposed bpf.