Efficiency degradation of short-distance wireless power transmission by distance alignment error

摘要

The optimal values of the circuit parameters with which the maximum efficiency of a short-distance wireless power transmission is attained, depend on the transmission distance. The distance dependence of the maximum efficiency and the optimal circuit parameters are numerically investigated by classifying the causes of efficiency degradation into impedance mismatching of the transmitting antenna, radiation loss, and ohmic loss. The degradation of the transmission efficiency by the distance alignment error when the circuit parameters are fixed to the optimal values is further investigated. It is shown that the degradation caused by impedance mismatching of a transmitting antenna is steeper than that caused by radiation and ohmic loss when optimised transmission distance is shorter than ∼0.1 λ.