3Department of Electronics and Communication Engineering, NIT, Tiruchirapalli, Tamil Nadu
Abstract — The design of a compact notch monopole antenna for application in ultra-wide band frequency domain is presented. The enhanced impedance bandwidth of the proposed antenna and a preliminary notch at 4.7 GHz are obtained by creating the square slot in the circular radiating element, an open ended slot is also created in the ground plane just below the microstrip feed-line and an open ended slit ring in the thick protruded stub erected from the upper portion of the square slot in the circular radiating element. The tuning of the notch frequency of 5.5 GHz in the WLAN band of 5-6 GHz as well as the further enhancement of notch is obtained by embedding a split ring resonator (SRR) in the left side of the microstrip feed line. The proposed UWB notch antenna provides the impedance bandwidth of 3.097GHz to 13.326 GHz (fractional bandwidth of 125%). The average measured gain of the proposed antenna is 7.1 dBi which covers the entire UWB band of operation except the notch band of WLAN. The group delay is consistent at around 0.2ns in whole of the UWB operating system except at the WLAN band where the measured group delay is around 2.8ns. The proposed UWB notch antenna exhibits consistent and stable radiation pattern. The equivalent circuit for the proposed UWB notch antenna is developed. Time domain performance of the proposed antenna is also examined from which it is clear that the proposed antenna is highly capable of handling the UWB short pulses in the UWB band of operation. Due to these novel characteristics of the proposed compact UWB notch antenna, it can effectively coexist with WLAN system and will find enormous application in the future wireless communication system.
Index Terms —monopole, ultra wideband, SRR, slot, slit ring, micro strip, time domain, Fidelity factor.