Tunable open ended planar spiral coil for wireless power transmission

A novel wireless power transmission (WPT) system with adaptive frequency tuning and a novel primary coil is presented. The primary transmitting coil is an open-ended single conductor spiral coil, where the traditional inductive resonator would include a secondary ground conductor. In addition, an Open-ended Spiral Coil (OSC) tuning technique has been applied to adjust the resonance frequency of the transmitting resonator to enhance the efficiency of the WPT system. The tuning method is found to improve the output DC voltage 60 percent after tuning the resonance frequency in nominal distance from 2cm up to 20cm with an excitation voltage of 20V at 13.54 MHz.