Abstract: This paper focuses on the design and simulation of a microstrip patch antenna for Wireless Sensor Network (WSN) applications, utilizing HFSS (High-Frequency Structure Simulator) software and an FR-4 epoxy substrate. The objective is to develop an efficient and cost-effective antenna tailored for the 2.4 GHz frequency band, commonly used in WSNs due to its favourable propagation characteristics. The choice of FR-4 epoxy substrate, with a relative dielectric constant (ࡾࢿ (of 4.4 provides a balance of performance, availability, and cost-effectiveness. These properties are crucial in determining the antenna's resonant frequency and overall efficiency. The design process involves optimizing the dimensions of the rectangular microstrip patch antenna to achieve the desired frequency and performance metrics. HFSS simulation tools are employed to model the antenna's behaviour, allowing for precise adjustments and performance predictions. Key parameters analysed include return loss (S11), gain, radiation pattern, and bandwidth.