A Novel UWB Filter with Notch-band Characteristic Using Radial-UIR/SIR Loaded Stub Resonators

Abstract

This paper presents a novel approach for designing compact ultra-wideband (UWB) bandpass filter with a good notched band characteristic. A notch band characteristic is obtained by using the radial-uniform impedance resonators (UIR)/stepped impedance resonators (SIR) loaded stub resonator. The main advantage of the proposed filter is that the frequency of the notched band can be tuned easily in a wide frequency range. Current density and equivalent model is also given depending on the odd/even excitation resonance condition. The characteristics of the filter are analyzed. To verify the proposed methods, two filters are designed and fabricated. Measured results show that the proposed UWB properties from 3 to 10.8 GHz and the notch band can be changed optionally from 4 GHz to 10 GHz. 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.