Maximum Sum-Power Wireless Reception: Some of the Antennas May Actually Radiate Positive Power

Considering a wireless power transfer system re-ceiving maximum power, we investigate just how different the power received by each antenna in a receive array can be. Antenna arrays are well described as ported networks, and circuit theory can be used to maximize power transfer given constraints. Combining circuit theory and electromagnetics we show that some antennas in the receive array can actually radiate positive power while the sum-power of the array is maximized. Additionally we explore the implications of this result with a numerical simulation of a wireless power transfer system using an acoustic model that demonstrates the power flux density and direction of waves in a linear-time-invariant medium.