Estimation of protection distance for RF field strength in quasi-far field around microwave WPT apparatus

In this paper, we measured electromagnetic field strength characteristics near the microwave WPT apparatus in the quasi-far field distance (in several meters) and investigated the method of estimating the protection distance from the station by calculating the electromagnetic field strength. For the measurement method and the protection distance calculation the investigation was made with reference to IEC 62232, and ITU-T K.52, K.61 which prescribes the safety protection evaluation method for installing the radio base stations of telecommunications carriers. As a result for this model with rectangular microstrip antenna, it was found that if the transmission power is 30 W or less at 915MHz, the protection distance is estimated within 0.5 m under the reference level satisfied.