Analysis, design and realization of a near-field focused RF power transfer system

  • R. van der Linden

Student thesis: Master


A wireless energy transfer system is designed to be used in one of the license-free and EIRP limited ISM bands. This system can be used for, e.g., powering wireless sensors. The EIRP is a parameter considered in the far-field. Therefore, we focus the power in the near-field of the antenna, simultaneously diffusing the power density in the far-field, thus leading to a lower EIRP compared to a non-focused antenna. Several adaptations to standard near-field focusing are investigated to increase the power density in the target region. The use of two orthogonal polarizations allow the use of two essentially independently steered focal spots. An array with rotated highly directive elements is capable of transferring the highest amount of power. An array consisting of 4 Yagi-Udalike elements utilizing this design can produce an average power density of 21.04 dBm/m2 at 2.45 GHz in a box of 10 x 10 x 10 cm3 located 1 meter from the array. If 8 Yagi-Uda-like elements are used, the power density increases to 24.34 dBm/m2, 8.3 dB higher than that of a single element.
Date of Award2013
Original languageEnglish
SupervisorHuib J. Visser (Supervisor 1)

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