This paper investigates the potential application of an Octagonal electromagnetic band gap (EBG) structure for patch antenna gain enhancement within the Industrial, Scientific, and Medical (ISM) band, spanning from 2 GHz to 10 GHz. The octagon geometry is strategically employed to harness the unique EBG properties, with a specific focus on optimizing the performance of a patch antenna with dimensions of 60 \(\,\times \,\) 60 mm \(^2\) . The EBG structure is meticulously designed to suppress unwanted radiation and interference, aiming to significantly improve the gain characteristics of the patch antenna across the specified frequency range. Through comprehensive simulation and analysis, this research unveils the efficacy of the octagon EBG in augmenting the patch antenna’s gain, providing valuable insights for the development of high-performance antennas tailored for diverse ISM band applications.