Optimal Design of Antenna Arrays Focused on Multiple Targets

This article presents an optimal design method for antenna arrays focused on multiple targets. The optimal design process is characterized by a quadratically constrained quadratic programming (QCQP). The complicated QCQP problem is solved by introducing a weighted diagonal matrix. The radiated power from the transmitting antenna array can be distributed among the multiple targets according to predetermined pattern by adjusting the weighted diagonal matrix. Once the positions of the targets and the predetermined field focusing pattern are all set, the test receiving antennas may be introduced to replace the targets, and the power transmission efficiency between the transmitting antenna array and the test receiving antennas is then maximized, which guarantees the maximum possible power delivery to each target in a focused manner. A unique optimal solution for the distribution of excitations can be found explicitly by analytically solving the QCQP. Several systems are designed for focusing the power to multiple targets in closed and open regions to demonstrate the focusing performance of the transmitting array excited with the optimized distributions of excitations obtained from QCQP.