Modeling of Human Body Shadowing Loss at 300 GHz Based on Measurement of Path Loss and Direction of Arrival

The modeling of the shadowing loss due to the human body in the 300-GHz band is important for the practical application of 300-GHz band wireless local area networks (LANs) and body area networks. In this study, the shadowing loss characteristics due to the human body was investigated by measuring the propagation loss and direction of arrival (DOA) of diffraction waves when a human body phantom blocks the line-of-sight (LOS) propagation path. The DOAs and the shadowing losses were measured by a terahertz hemispheric scanner and vector network analyzer (VNA). For a human body phantom positioned upright with a gap between the arms and torso, the removal of the arms increased the shadowing loss by more than 10 dB. DOA measurements revealed a reduction in the shadowing loss upon attachment of the arms, attributed to the additional propagation path created by diffraction inside the arms. The shadowing loss for a human body with arms could be estimated using a model comprising a double-isolated-knife-edge diffraction (DIKED) model for the torso and a single-knife-edge diffraction (SKED) model for the arm when a gap exists between the torso and arms. By comparing with actual measurement values, we demonstrated that this method can estimate the diffraction at the head and torso. When the phantom without arms was dressed in a down coat, the shadowing loss decreased by approximately 9 dB because the scattering induced by the down coat broadened the DOA of the received radio wave diffracted at the side of the torso. When the phantom's head was covered with a wig, the shadowing loss at the head reduced by approximately 2.8 dB due to scattering by the wig. These results indicate that arms, hair, and clothing have a significant impact on shadowing loss by the human body at 300 GHz. The human body shadowing (HBS) loss was successfully calculated using the DIKED model with the effects of arms, hair, and clothing added as correction terms.