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 ۳.۱ to ۱۰.۲ GHz with only ۰.۱ dB insertion loss. This wide pass band of ۷.۱ GHz, shows ۱۰۶.۷% 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 ۱۲.۸ to ۲۸.۲ GHz with more than ۲۰ 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 ۱۱.۷ mm × ۷.۲ mm (۰.۳۵ λ × ۰.۲۲ λ), where λ, is calculated at the center frequency of ۶.۶۵ GHz. The proposed device is simulated, fabricated and tested. The measured results confirm the correct performance of the proposed BPF.