SAR Calculation in a Simulant Human Body which is between the Transmitter and Receiver of the

Wireless Power Transmission System Young-Jun Ju 1, Yu-Ri Lee 1, Dong-Yeol Lee 1, #Yoon-Myoung Gimm 1

1 Department of Electronics and Electrical Engineering, Graduate School, Dankook University 126, Jukjeon-Dong, Suji-Gu, Yongin-Si, Gyeonggi-Do, South Korea,

kusa@dku.edu, myuri2@naver.com, luis7figu@naver.com, gimm@dku.edu

Abstract Self-resonance wireless power delivery systems operating at 128 kHz and 13.56 MHz were

designed. SAR (Specific Absorption Rate) of homogeneous human body between the transmitter and the receiver and resonance frequency of the wireless system were calculated. Keywords : SAR Calculation Simulant Human Body Wireless Transmitter System 1. Introduction

Although wireless power transfer technology was suggested by Nikola Tesla, it has not been

deeply studied until self-resonance technique was announced by Marin Soljačić in 2007[1]. Usually wireless power transfer is performed by applying magnetic field and its facilities are installed where people resides, so evaluation of human body effect by the magnetic field became very important.

Self-resonance wireless power transfer system was designed at 128 kHz and 13.56 MHz, and homogenous numerical human body was installed between the transmitter and the receiver.

The reasons of 128 kHz and 13.56 MHz for wireless power transfer system are that 128 kHz is used for MFAN(Magnetic Field Area Network)[2] and 13.56 MHz is in a ISM band which has variables usage including RFID and NFC(Near Field Communication).

2. Self-Resonant Wireless Transmitter System

Fig. 1 shows schematic diagram of self-resonance wireless power transfer system[1]. This system is more efficient than the other systems at near distance applying the resonating auxiliary coils.

Figure 1: Self-resonance wireless power transfer system using the resonance coils.

3. Reference Values of Human Body Protection of Electromagnetic Fields

Because of the possibility that electromagnetic fields can affect human health, many national and international EMF protection guidelines were provided. Table 1 shows basic restrictions of SAR values for frequencies up to 10 GHz[3].

Point SAR value is defined as absorption power per unit mass of the human body at a point.

SAR x, y, z σ x, y, z |E x, y, z | /2ρ x, y, z (1) σ x, y, z Conductivity of the medium at x, y, z including dielectric loss ω ′′). E x, y, z = Vector phasor of E-field at (x, y, z). ρ x, y, z = Mass density of the material where SAR value is to be evaluated.

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