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.