WPT by a pair of short helical dipoles

Wireless power transmission (WPT) by two short helical dipoles arrayed orthogonally is presented. For the electric resonance coupling WPT system, the short dipoles need for a matching circuit due to cancel its large capacitance at the operating frequency. In the proposed method, the loss is reduced by using the helical structure instead of matching circuit. Its power transmission characteristics are shown in experiments. The measured results are agreed with the calculated results of a pair of dipoles with a matching circuit. In the orthogonal arrangement, the WPT is possible in the wide range expect for the angle θ = 0 between the antennas. At θ = π/4, the coupling coefficient becomes the maximum, and the WPT is enabled for the longest distance.