Design and measurement of WPT system for various load resistances using oscilloscope

The authors propose a new WPT design and measurement method. A conventional method using VNA has to set input/output ports as 50 ohm. But the input/output resistance of many WPT systems is not 50 ohm. On the other hand, WPT system is designed by 2-stage band pass filter theory with resonator parameters. A new method uses an oscilloscope for the measurement of resonator parameters, such as resonant frequency, Q value and coupling coefficient, which are necessary for WPT design. Because they are calculated from voltage variation measured by an oscilloscope, the method is free from 50 ohm condition. Therefore, the proposed method is suitable for WPT system design with 0 ohm power source and various load resistances.