Electric Field Resonant Antenna for Wireless Power Transfer Based on Infinitesimal Dipole

Electric field resonant antennas for wireless power transfer using the near field generated by an infinitesimal dipole are proposed. Since the radiating parts of the antennas are composed of thin metal electrodes, it is suitable for making thinner and lighter than magnetic field resonant antennas formed by coils. In addition, there is no heat generation in the surrounding metal due to induction heating, which makes it particularly effective for high-power transmission systems. Since the electric field in the near field has both longitudinal and transverse component, there are two types of electric field resonant antennas: those that use the longitudinal wave of the electric field and those that use the transverse wave. We have made prototypes of each type of antenna with resonant frequency of 13.56 MHz and compared their structures and characteristics. Having near field antenna as wireless power transfer coupler comes with several advantages, one particular example is coupler's alignment tolerance enabled by longitudinal electric field component. Electric field resonant antennas were also found to transmit power through the electric near field that was inversely proportional to the cube of the distance.