Microstrip or Patch antenna consists of a radiating patch on oneside of a dielectric substrate which has a groundplane on substrate supports both linear as well as circular polarization. Dimensions of a Microstrip patch antenna depend on the resonant frequency and value of the dielectric constant. Patch antennas are lowcost, have a low profile and are easily fabricated.These antennas are becoming increasingly useful because directly they can be printed onto a circuitboard. Microstrip antennas are becoming very widespread within the market of mobile phone.In this paper the design and simulation of a circular patch antenna for wireless local area network(WLAN) application is presented. Modelling antenna as a wide role into play from the perspective of an electro magnetic engineer, as it avoids severalfailure steps of fabrication.It also enhances the features the anticipated results earlier to measurements.In this way re engineering is made easy. WLAN application typically needs antenna operating at 2.45 GHz and 5.1 GHz. In this work circular patch antennas are simulated using High Frequency Structure Simulation(HFSS) tool. Various reports like return loss, VSWR, gain, radiation pattern analyzed and compared with that of the rectangular patch antenna.