Far-field radiation and near-field leakage of self-resonant spiral antennas for coupled-resonant wireless power transfer

Far-field radiation and near-field leakage for coupled-resonant wireless power transfer are discussed. At first, wire-winded antenna is examined as a basic model. As an alignment of transmitting and receiving antennas, normal arranged model and reverse arranged model are considered. Numerical simulation demonstrated that far-field radiation power of the reverse arranged model is 9.3dB smaller than the normal arranged model. Considering 1kW power transfer, the reverse arranged model requires 15% smaller clearance that complies with ICNIRP guidelines than the normal arranged model. Next, dielectric loaded tape structure antenna is investigated. We found that this structure has 35.1% lower resonant frequency, compared to the wire model. Far-field radiation power of this structure is 8.4dB smaller and clearance for ICNIRP guideline is 13% larger than the wire model.