Compact UWB filter using inverted-T stub to stop IEEE 802.11a narrowband service

In this paper, we present a compact filter that is proposed by interconnecting microstrip with Coplanar Waveguide (CPW) structure using broadside coupling to eliminate the interference from IEEE 802.11a to Ultra-Wideband (UWB) systems. The Chebychev Type II is considered as filter design model to stop the entire WLAN spectrum ranging from 5.15 GHz to 5.875 GHz. In order to avoid the effect from this WLAN range, the filter is designed by considering -10 dB stopband from 4.6 GHz to 5.94 GHz with steeper attenuation of 21.69 dB. With the above features and comparable performance with the other filters suggested in the literature, the best size reduction achieved by the designed filter with the total size of 16 mm × 16 mm is 76%. Also, it is observed that the phase response of the filter is linear over the passband.