This paper presents a study of a coplanar waveguide (CPW-fed) antenna using a Modified Ground Structure (MGS). The antennas studied are relatively small in size (17 x 20) mm2 and was designed on a low-cost FR-4 substrate. The presented antenna models shows improvements in the impedance bandwidth, the center frequency and operating bands with the stages of modification being introduced in the ground structure. The designed antennas were simulated using Ansoft HFSS, a FEM based simulator and antenna’s characteristics such as Reflection coefficient, Center frequency, Operating frequency bands, Impedance bandwidth, and VSWR are reported in this paper.