Electromagnetic Bandgap Structures (EBGS) have emerged as an effective technique for suppressing undesired harmonic components in microwave and RF systems. Harmonic distortion degrades signal integrity, reduces power efficiency, and increases electromagnetic interference in communication and power electronic circuits. This research presents the design and simulation of an EBGS based microstrip bandpass filter aimed at achieving compact size, sharp selectivity, and effective harmonic suppression. The proposed structure integrates periodic defected ground plane patterns beneath a microstrip transmission line to create frequency selective stopbands while preserving passband characteristics. MATLAB based modeling and full wave electromagnetic simulations were performed to analyze S parameters, insertion loss, return loss, and harmonic rejection performance. The results demonstrate that the EBGS based bandpass filter significantly attenuates second and third harmonics while maintaining low insertion loss within the desired passband. The proposed design provides improved selectivity and compactness compared to conventional microstrip bandpass filters. The study contributes to the advancement of high-performance filtering solutions for wireless communication systems, radar applications, and RF front end modules.