A Weighted Method for Multibeam Synthesis With Controllable Gain and Sidelobe Suppression

In this article, a weighted method is developed for the design of antenna array to generate multiple beams with sidelobe suppression. While the method guarantees that the radiation energy in the far-field region is maximized, the energy distribution of the multiple beams can be controlled by adjusting the weights introduced during the optimization process. A new performance indicator is introduced and optimized to suppress the sidelobe level (SLL) of the shaped pattern based on the extended method of maximum power transmission efficiency (EMMPTE). Moreover, the weights are adaptively searched by the particle swarm optimization (PSO) to precisely control the SLLs and the gain distributions of the multiple beams in the designated region to meet various design requirements. As a verification, the radiation patterns of single- and dual-beam configurations with SLL suppressions, and a tri-beam configuration with specific gain distributions, are studied by using a 12-element linear antenna array. The optimized distributions of excitations obtained from the method are realized by a digital feeding circuit. The measured results demonstrate that the proposed method is capable of shaping the main beams and controlling the sidelobes in the targeted directions, providing a new and efficient strategy for pattern synthesis. Compared to optimizing the excitations of antenna arrays to achieve desired shaped patterns directly using PSO or other optimization algorithms, the optimization procedure implemented in this article requires significantly less computational time due to the reduced number of variables and iterations involved, especially for large antenna arrays.