Compact band-notched UWB BPF with enhanced pass-band characteristic

This paper presents a novel approach for designing compact band-notch ultra-wideband (UWB) bandpass filter with a good enhanced pass-band characteristic. Notch-band and enhanced pass-band characteristic are obtained by using the radial-cross loaded stub at the same time. The main advantage of the proposed filter is the pass-band can be expanding to including the whole WLAN band. Equivalent model is given depending on the odd/even excitation resonance condition. The characteristics of the filter are analyzed. To verify the proposed methods, filter is designed and fabricated. Measured results show the proposed UWB properties from 2.2 to 10.4 GHz and the notch band can be changed optionally from 4GHz to 7GHz. These filters can be integrated in UWB radio systems and efficiently enhance the interference immunity from undesired signals such as wireless local area network (WLAN) and WiMAX.