High-Efficiency Wireless Power Transfer With Tightly Coupled Antenna Arrays

In this communication, the use of tightly coupled antenna array (TCAA) for radiative wireless power transfer (WPT) implementation is discussed; such arrays exhibit very high radiation efficiency, also thanks to their reduced antenna spacing, which make them a good candidate for the realization of high-efficiency WPT links. A dual-orthogonal polarization TCAA unit cell design based on an infinite array equivalent model (IAEM) is described, focusing on the maximization of the broadside efficiency instead of the conventional TCAA optimization of ultrawideband and wide scan angle stability performance. A numerical methodology for the evaluation of the achievable power transfer efficiency (PTE) is discussed, showing the key role of a close antenna spacing in achieving high efficiency. Finally, results of the experimental analysis done at 2.45 and 3 GHz with two TCAA prototypes excited with equal amplitude/phase feed networks are reported, confirming that TCAAs perform very close to the continuous aperture (CA) limit.