In this article, design and analysis of a modified circular slot antenna is discussed. The proposed antenna design is attractive because of two important reasons: (i) modified circular slot creates dual operating bands; (ii) stable radiation characteristics over the operating frequency bands are observed. The complete analysis of proposed radiator has been done on Ansys HFSS simulation software. For verifying the simulated outcomes, a prototype of antenna structure is fabricated and tested. Measured results show that the proposed antenna operates over two frequency bands, i.e., 2.88-3.92 GHz and 5.26-6.28 GHz with the fractional bandwidths of 31% and 17% respectively. Experimentally measured average gain of the proposed radiator is 3 dBi and 6 dBi in lower and upper frequency bands, respectively. All these features of the proposed antenna make it appropriate for WiMAX (3.5 GHz) and WLAN (5.8 GHz) applications.