Design and analysis of Circular microstrip patch antenna with SRR on modified and defected ground structures for UWB applications

Modified split-ring resonators (SRR) are used develop a high gain UWB antenna for microwave imaging applications. This paper analyzes two different ground designs for the proposed patch radiator with modified SRR; defected ground structure and the second one is rectangular slotted ground. Two SRRs are placed on the circular radiator patch element, each in the shape of alphabet letters ‘S’ and ‘V’. The results of the first design with DGS demonstrate that the reflection coefficient is well below −10 dB in the frequency range from 1.9 GHZ −11.9 GHz with the fractional bandwidth of 110%. Further modification in the resonant modes of UWB is obtained by introducing single rectangular slot on the ground plane. This helps in eliminating the lower band from 1.9 GHz to 6 GHz. This band rejection helps in alleviating the interferences caused by other unlicensed wireless applications lying in sub 6GHZ band.