A microstrip exponential-square patch antenna have been proposed and simulated in this paper. It consists of an exponential-square patch, a substrate, a square ground plane and probe feed. The exponential-square patch shape is modified from conventional square geometry with two parallel side replaced by two exponential curve. From simulation results, it is shown that microstrip exponential-square patch antenna has wider bandwidth, lower return loss, higher gain, within same radiation pattern and same beam width compared to conventional microstrip square patch antenna. The proposed antenna is designed and simulated at 3 GHz frequency operation suitable for S-Band radar application.