Reconfigurable Wireless Power Transmission in Fully-Enclosed Space Using Antenna Array

Abstract

This paper studies employing antenna array to reconfigure wireless power transmission in fully-enclosed space (that is, environments enclosed by conducting walls, such as spacecrafts and engine compartments). Because strong coupling may appear among array elements, conventional phased array is not the best approach. We find parasitic array, which includes one driver element and multiple parasitic elements, an excellent candidate to achieve high power transmission efficiency in fully-enclosed space. Phased array and parasitic array are analyzed and compared with each other; closed-form expressions of maximum power transmission efficiency are derived when the array includes two elements. With the theoretical analysis as guideline, some experiments are conducted in a cubic box with size of 1 cubic meter and with aluminum walls. Experimental results demonstrate that, parasitic array offers higher power transmission efficiency than phased array in most of the scenarios. To be more specific, the power transmission efficiency could always reach 90% when a parasitic array includes 4 elements (i.e., 1 driver element and 3 parasitic elements) and when the receiver changes its location in a 60 cm by 60 cm region.