ULTRA-WIDEBAND BANDPASS FILTERS WITH A CONTROLLABLE AND HIGHLY SELECTIVE NOTCH-BAND

摘要

In this letter, a novel band-notched ultra-wideband (UWB) bandpass filter (BPF) is investigated. A structure of complementary two turns spiral resonator (CSR2) is proposed to improve notch performance of the UWB BPF. The single CSR2 unit cell has a size of 0.08λ_g×0.08λ_g(what is kg) at stop-band center frequency (5.7 GHz). With respect to the resonance nature of the miniaturization and high Q value, a compact UWB BPF with multiple CSR2s is designed. The proposed filter demonstrates band-stop-filter-like response with high frequency selectivity and controllable bandwidth at rejection band. We assess the filtering behavior of structures from two aspects: the return loss and the group delay. The measured notched band frequency is range from 5.05 to 5.85 GHz(|S_(11)|<-10dB). The maximum attenuation is more than 28 dB at the central frequency of 5.37 GHz. The measured and simulated results are well-complied with each other.