Microstrip Patch Antennas (MPAs) play a critical role in modern wireless communication systems due to their compact size, easy integration, and capability to ensure reliable communication across wide frequency ranges. This paper introduces enhanced designs of rectangular MPAs aimed at overcoming the narrow bandwidth limitation commonly found in traditional designs. Three innovative configurations are proposed: one featuring a simple rectangular slot on the ground plane, another integrating polygonal Defected Ground Structures (DGS), and a third utilizing rectangular DGS. These antennas are optimized at a frequency of 4 GHz using High Frequency Structural Simulator (HFSS) software to significantly improve antenna performance. The MPA without DGS showed a return loss of -21.124 dB at a resonant frequency of 4 GHz, with a Voltage Standing Wave Ratio(VSWR) of 4.8038 and a gain of 3.88 dBi. In contrast, the MPA with Polygonal DGS exhibited significant improvements, achieving a return loss of -26.87 dB at a resonant frequency of 4.1 GHz, along with a VSWR of 1.3721 and a gain of 4.38 dBi. Similarly, the MPA with Rectangular DGS demonstrated superior characteristics, with a return loss of -27.08 dB, resonance at 3.825 GHz, a VSWR of 1.4399, and a gain of 4.00 dBi. These results underscore the effectiveness of DGS in broadening the bandwidth and improving the performance of MPAs for applications below 6 GHz, making them highly suitable for next-generation wireless communication systems.