Design and Development of a Microstrip Antenna Array with Beamforming Network Integration for Enhanced Gain and Directivity at 3.5 GHz

This study addresses the challenges of designing efficient antenna systems for intermediate frequencies, such as 3.5 GHz, a band that is often overlooked in favor of millimeterwave and 5G applications. The need for high-gain, directional antennas with beamforming capabilities has become increasingly important for modern wireless communication systems to ensure reliable signal transmission and reduced interference. To tackle these challenges, this research focuses on the design and optimization of a $\mathbf{3 x 1}$ microstrip patch antenna array integrated with a branch-line coupler feeding network. Using CST Microwave Studio, the system was refined to achieve strong gain (12.49 dBi), low side lobe levels, and stable beamforming. Reflection coefficients of -31.99 dB and bandwidths ranging from $\mathbf{1. 8 \%}$ to $\mathbf{2 5. 8 \%}$ validate the design’s effectiveness. Although slight phase shifts were observed, the system maintains reliable performance, demonstrating its suitability for applications requiring efficient, high-gain communication. This study provides a practical solution for beamforming at intermediate frequencies, addressing existing gaps in the field and contributing to the advancement of nextgeneration wireless communication technologies.