Abstract: This paper presents the design and comprehensive analysis of a 9 GHz inset-fed rectangular microstrip patch antenna intended for X-band applications. Microstrip patch antennas are widely recognized for their low-profile structure, ease of fabrication, and seamless integration with modern microwave circuits, making them suitable for radar, satellite communication, and defense systems. The proposed antenna is designed and simulated using Ansys HFSS software on four distinct substrate materials, FR4, air, Bakelite, and Rogers RT Duroid 5880, with dielectric constants of 4.4, 1.0, 4.8, and 2.2, respectively. The study emphasizes the impact of substrate material on antenna performance by evaluating critical parameters such as return loss, gain, directivity, bandwidth, and VSWR. Simulation results demonstrate that FR4 provides the best impedance matching with a return loss of –37.13 dB, while the air substrate offers maximum gain of 9.58 dBi. Rogers 5880 achieves balanced performance in terms of gain and return loss, making it suitable for high-performance applications despite higher fabrication costs. Bakelite shows moderate performance but remains viable for low-cost solutions. This investigation highlights the trade-offs between performance and cost in substrate selection, offering antenna designers practical guidelines for optimizing X-band antenna designs. The findings contribute to improving antenna design strategies for reliable communication systems operating in the X-band spectrum.