Three-Dimensional Flat-Top Beam Shaping for Planar Antenna Arrays Based on the Method of Maximum Power Transmission Efficiency

This letter presents an optimization method for the design of a shaped-beam antenna array (SBAA) based on the method of maximum power transmission efficiency, addressing the limitations of traditional beamforming techniques in flexible pattern synthesis. The proposed approach enables the efficient generation of various far-field flat-top patterns according to practical requirements through a far-field optimization process. By configuring an SBAA as transmitting and deploying several virtual test antennas in the far-field region as receiving, the optimal excitation distribution is analytically derived by maximizing power transmission efficiency under an equal constraint on the received power. To validate the proposed method, a 4×4 SBAA along with a radio frequency circuit capable of providing adjustable amplitude and phase excitation, was designed, fabricated and tested. The feasibility of generating three types of flat-top radiation patterns—including square, circular, and annular shapes—has been demonstrated through both simulations and experimental measurements. The measured results show that the effective flat-top coverage for both the square and circular patterns spans the angular range from –30° to 30°, with the gain fluctuation maintained below 1 dB. The proposed design offers a flexible and time-efficient approach for precise flat-top beam shaping, making it suitable for deployment in 5G/6G base stations and indoor communication systems.