In this paper, a novel circularly polarized, dual-frequency, slotted square patch is designed, implemented and measured. This patch is designed by applying electromagnetic band-gap (EBG) structures in the ground plane under the slots with probe feeding mechanism to operate at 2.25 GHz and 3 GHz. Five different schemes of periodic defects are applied to its ground plane and compared using 3D EM simulation. The one with periodic etched circles under the dual frequency slots
is found to be the best. Hence, a parametric analysis is performed to obtain the optimum values of the antenna physical dimensions. It exhibits superior performance enhancement compared to the same antenna that was designed and
optimized without applying EBG structure. The enhancement in its performance is noticed as higher gain, wider bandwidth, better VSWR and axial ratio, without degrading any other parameter. Measurements are in good agreement with simulations, which verifies the design procedure and strongly recommends the proposed element for telemetry, telecommand and control (TT&C) satellite antenna systems.