Wireless Power Transfer by Means of Electromagnetic Radiation Within an Enclosed Space

TL;DR

This paper investigates wireless power transfer via electromagnetic radiation within enclosed spaces, deriving formulas for efficiency and showing that reflecting surfaces can significantly enhance long-range power transfer.

Contribution

It introduces formulas for transfer efficiency in various environments and highlights the impact of reflecting surfaces on improving long-range wireless power transfer.

Findings

Reflecting surfaces can substantially increase efficiency at long distances.

An upper limit for transferred power is established under absorption constraints.

Efficiency formulas are derived for free space, reflecting surfaces, and enclosed spaces.

Abstract

In this paper, wireless power transfer by means of electromagnetic radiation is investigated. Formulas are derived for the efficiency of the power transfer in free space, in the presence of reflecting surfaces, and within enclosed spaces. It is found that the presence of reflecting surfaces has the capacity to substantially enhance the efficiency of power transfer at long range. An upper limit is also found for the transferred power when constraints are imposed on certain forms of undesired absorption. For the sake of simplicity, only the efficiency of the radiative power transfer is considered. Losses due to resistance in the antenna structures or inefficiencies in RF to DC conversion are neglected.