Reduction of specific absorption rate (SAR) in human body by a lossy dielectric shield

Although many studies on the biological effects of electromagnetic waves have been reported, there are few reports on protection of the human body against EM waves. In this paper, we consider a situation where a person is exposed to a plane wave (TM wave) with a frequency of 300 MHz (resonant frequency of human body) and a power density of 1 mW/cm2 in an immunity test. In this situation, we propose a protection method in which the person is positioned behind a semicircular shield made of lossy dielectric installed in the test room. The specific absorption rate (SAR) inside a cylindrical human model is calculated. Here, as an example, the case where the shield can reduce the SAR to half the value for the model without the shield is considered, and the reduction effect of the shield is discussed. In the immunity test, it is necessary to avoid effects on the test equipment caused by scattered waves from the shield and the human body. The scattering patterns are also examined. The calculated results show that the SAR and the scattering patterns are significantly changed not only by the permittivity and the width of the shield, but also by the position of the human model. © 1998 Scripta Technica, Electron Comm Jpn Pt 1, 81(10): 71–80, 1998