Bandwidth Enhancement of Small Slot Antenna with a Variable Band-Stop Function

In this paper, a novel and compact design of microstrip slot antenna with band-notched characteristic for UWB application is proposed. In the proposed design, an inverted T-shaped slot at the square radiating stub is used to create an additional resonance at the higher frequencies. By obtaining this resonance, the usable upper frequency of the antenna is extended from 10.3 to 17.6 GHz which provides more than 140 % fractional bandwidth. Additionally, by cutting a pair of step-shaped slits in the ground plane, a desired frequency band-stop performance has been obtained. Experimental results obtained for this antenna show that it exhibits good gain and radiation pattern characteristics within the UWB frequency range. The proposed antenna can operate from 2.9 to 17.1 GHz for VSWR <2 with a rejection band around of 5–6 GHz to suppress any interference from wireless local area network systems. Simulated and measured results are presented to validate the usefulness of the proposed antenna structure for UWB applications.