Resonator based compact ultra-wideband and notched wideband filters

In this paper, three ultra wideband (UWB) bandpass filters using microstrip with wide passband, low insertion and return loss are presented. The proposed filters cover the UWB indoor mask range from 3.1 GHz to 10.6 GHz. The first filter has a circular plate resonator with interdigital coupling has been designed to act as bandpass filter with passband of 8.25 GHz. The second filter is achieved using equilateral octagonal structure by connecting its open stub to ground plane through via-hole. The third filter, which is derived from the first filer is designed to introduce notch in the frequency range from 4.85 to 5.85. The designed filters are successfully simulated by electromagnetic simulator, IE3D. The filters exhibit low insertion loss over the desired passband, and a good out-of-band performance.