Optimal Design of Multitarget Wireless Power Transmission With Arbitrary Received Power Allocation

The inappropriate power allocation among multiple targets may lead to low power transmission efficiency and thus the waste of available power sources in multitarget wireless power transmission (WPT) system. This letter proposes an efficient method, called the weighted and constrained method of the maximum power transmission efficiency, for the optimal design of transmitting antenna array for multitarget WPT applications. By introducing the weighting coefficients for the test receiving antennas, the radiated power is maximally concentrated towards the targets to be powered and suppressed at others in 3-D space. Furthermore, the power allocation among the targets can be precisely controlled according to practical requirements. Two WPT systems with different power allocation schemes among the targets are investigated. Both simulation and measurement results indicate that the power is distributed among the targets as scheduled inside the enclosed 3-D space. Four different power allocation schemes of 1:1 and 2:1 in the two-target case and 1:1:1 and 3:2:1 in the three-target case are achieved while the corresponding power transmission efficiencies for the above four situations reach 23.76%, 23.63%, 20.61%, and 19.04% at 5.8 GHz, respectively.