In this paper, a rectangular microstrip patch antenna is designed using HFSS software. The designed antenna has a resonating frequency of 2.4 or 2.5 GHz which is applicable to Wireless Local Area Network (WLAN). This paper shows the design considerations of the proposed antenna as well as the simulated results of the same. The design is made on material like Polyester used as a dielectric material with its dielectric constant and thickness of 3.6mm. The proposed antenna is then fabricated on the basis of the simulated design in HFSS simulation software. Also, comparison some material to obtained the results. The simple structured configuration and low profile of the proposed antenna makes the fabrication process easy and also suitable for the application in the WLAN.