Development of Measurement Phantom for Absorbed Power Density Assessment by Human Exposure at 28 GHz Band

In recent years, the guidelines/standards of human exposures to electromagnetic fields have been revised and a new metric referred to as absorbed/epithelial power density (APD) is specified as the basic restriction in the frequency range from 6 to 300 GHz. In this paper, we focus on the development of low-loss phantoms that can model the electromagnetic interaction between an antenna/device and skin in the quasi-millimeter and millimeter-wave frequencies using electromagnetic simulation. The phantom will be used for APD assessment based on field measurement at 28 GHz. It was found that polyphenylene-ether (PPE), which is typically used for antenna substrates, enables the accurate assessment of APD on the skin surface regardless of the antenna type, and that it is rendered suitable as a phantom for APD assessment by optimizing the thickness of low-loss materials with respect to relative permittivity in the range from 10 to 28.5 at 28 GHz.