Design of Ultra-wide Band band-pass filter with notched band at 802.11a Frequency Spectrum using multi-mode ring resonator

The existence of WLAN Application over Ultrawide Band Spectrum becomes a challenge for development of UWB Applications. Hence, in this paper, an ultra wideband bandpass filter (UWB-BPF) with notched band at 802.11a Frequency Spectrum is proposed. The proposed filter is designed by using multimode ring resonator. The multimode ring resonator is represented by rectangular ring which is connected to the interdigital capacitor. The proposed filter is printed on the Duroid substrate with relative permittivity and thickness of 2.2 and 1.6 mm, respectively. The designed filter occupies the area of 36 mm × 16 mm. The proposed filter characteristics are investigated numerically and experimentally in terms of return loss, insertion loss, surface current, phase and group delay. From the numerical analysis, it shows that the proposed filter has a pass-band at frequency of 3.78-7.94 GHz with notched band at 4.3-5.9 GHz. This result is very useful to reject IEEE 802.11a based services over the UWB Applications. However, the experimental analysis shows different performances both in the operating pass-band and insertion loss. This difference may be occurred due to the technical reason while conducting filter measurement.