Circular microstrip antennas have several interesting properties that makes it attractive in wireless applications. A circular microstrip antenna is designed in order to obtain the required parameter responses from 2.7 GHz to 2.9 GHz by using IE3D software based on the method of cavity model due to simplicity and ease of analysis. The circular microstrip antenna is fed by a coaxial probe (Teflon probe) and glass epoxy is used with the specified information include the dielectric constant of substrate ( fr = 4.2), the resonant frequency (fr = 2.8 GHz) and substrate height (h=1.6mm). The circular microstrip antenna exhibits appropriate required parameters depend on the feedpoint position, size of the circular patch. A prototype of a circular microstrip antenna has been built and tested by spectrum analyzer. There is slight difference between the measured and simulated results caused by several factors that would be discussed in result part.