A novel beam steerable antenna array system for 5G mm-wave applications

Official URL: https://risc01.sabanciuniv.edu/record=b2758678_(Table of contents)

This thesis proposes a novel, low-cost, wide-angle beam steerable microstrip antenna array system for 5G 28 GHz mm-wave band applications. The final system consists of two branch-line couplers on the perpendicular sides and one butler matrix on the main side of the final structure, together with their corresponding Chebyshev tapered antenna arrays. Unlike the conventional 4×4 Butler matrix and branch-line coupler feeding, which generally can generate 4 and 2 beams, the designed configuration employs a novel feeding technique that allows the system to generate 7 beams for the butler matrix and 3 beams for the branch-line coupler. The final system covers a wider spatial range due to its unique placement of the branch-line couplers and 2×10 array antennas perpendicular to the sides of the main beamforming and the 4×10 array antenna architecture. The measured gain for the 13 beams varied between 11.2 and 14.1 dBi at 28 GHz. A wide impedance bandwidth for the entire 26.5 to 29.5 GHz band was achieved, while more than a 10% fractional radiation bandwidth was obtained with a gain value over 10 dBi. Furthermore, to enhance the radiation bandwidth of the system, a novel slot-loaded unit element is designed and optimized for the corresponding beamforming network to operate at the band of interest. The proposed design’s overall performance was verified, and a low-cost PCB prototyping technique was used for fabricating. Later the fabricated design’s reflection coefficients and radiation patterns were measured. The final system’s lowcost, wide beam coverage and improved realized gain values make it suitable for 5G mm-wave handset applications