This project focuses on designing and simulating a rectangular microstrip antenna using HFSS software for wireless communication applications. Microstrip antennas are popular because they are small, lightweight, low cost, and easy to install. In this work, important antenna parameters such as gain, bandwidth, return loss, and radiation efficiency are studied. The antenna is designed to operate at 2.25 GHz. The results show that factors like substrate material, feeding method, and antenna shape greatly affect performance. A corporate-feed rectangular patch array antenna provides higher bandwidth, better efficiency, and improved directivity compared to a simple rectangular microstrip antenna. These findings show that HFSS-based antenna design helps in achieving better performance, making microstrip antennas suitable for WLAN, radar, aircraft, spacecraft, and satellite communication systems.