A Comparative Study between Different Loop Antennas Topologies for Wireless Power Transmission based on Modal Analysis

Wireless power transfer (WPT) using magnetic coupling between loop antennas is an emerging technology, which could solve difficulties and hazardous technical problems of wired power transmission. From several millimeters to several hundred millimeters, WPT technology has reached kilowatts power level with high grid load of efficiency, which has brought significant benefits to medical applications, automation systems, consumer electronics, etc. Yet, WPT systems are extremely sensitive to the alignment between the transmitting and the receiving coils. A dual transmitter topology has been proposed to overcome the misalignment problems and maintain high power transfer efficiency. Nevertheless, the misalignment sensitivity between the transmitters was not considered. A comparative study based on the Theory of Characteristic Modes between three different topologies of the transmitting systems in MHz level is conducted in this paper. To enhance the comparison, the power transfer efficiencies of the three models are calculated regarding the same positions of the receiver.