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A novel design of a circular patch antenna having Z‐shaped defected ground structure is presented in this communication. The antenna is designed for X‐band applications. A wideband is obtained in the X‐band frequency range 8–12 GHz. The return loss and input impedance is measured experimentally and compared with the simulated results. Parameters like impedance bandwidth, voltage standing wave ratio, and antenna gain are calculated and discussed. Impedance bandwidth of about 1.2 GHz is obtained with a gain of 8.7 dBi and side lobe level of −20.1 dB. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2251–2254, 2013

Abstract-This paper presents a novel design of a circular ring defected ground structure (DGS) antenna for bandwidth enhancement using fuzzy logic approach. The ground plane of the antenna is defected by introducing circular ring sector type of defect beneath the circular ring patch. The position of the defect in the ground plane to attain the highest return loss and corresponding frequency is determined by using Fuzzy Inference System (FIS). The antenna resonates in X-band showing wideband characteristics with improved gain and reduced cross polar components. The return loss and analogous frequency obtained from simulated results and fuzzy system are compared and are in good agreement. The return loss and input impedance is measured experimentally and compared with the simulated results. Parameters like impedance bandwidth, VSWR and antenna gain are likewise calculated and discussed. The simulated results for the radiation pattern of the proposed design with polarization (Co-polar and Crosspolar) are also presented. The simulated impedance bandwidth of about 1.33 GHz (1.2 GHz experimentally) in X-band is obtained with a gain of 6.43 dB and also cross-polarized radiations have an isolation of 20 dB.