Optimal design for a class of spherical helical antennas applied in wireless transmission of energy by resonant coupling

Method of selecting the optimal antenna design for a mid-range wireless transmission of energy is applied on a class of spherical helical antennas in the paper. The effect of finite conductivity of wires on transmission performances and some methods for counteracting it are considered. It is shown that the selection of optimum antenna design depends neither on surface resistance nor on radius of conductor. Also, by cooling antenna conductors and by using the multiple folding concept one can reduce significantly the electrical size of the sphere needed.