Evaluation of Stored and Absorbed Power of a Normal-Mode Helical Antenna in a Human Body Condition

A normal-mode helical antenna (NMHA) is commonly used as a human body sensor for human health care applications. It was reported that the conductivity of a human body significantly affects the antenna’s electrical performances. This study analyses the performance of NMHA in the human body condition. The objective is to investigate how the conductivity of human tissue affects the antenna’s electrical characteristics such as stored power, absorbed power, and input resistance. Electromagnetic simulations were performed using the FEKO 2019 simulator to assess the electromagnetic field distribution, Poynting vector, and electric power relationships in human body tissues. The time-dependent behavior of stored electric and magnetic powers was examined, revealing that they alternate over time. The results demonstrate that increasing tissue conductivity reduces both stored and absorbed power, as evidenced by a decrease in the Poynting vector magnitude. Moreover, the radiated power distribution area shrinks in higher conductivity environments due to the presence of absorbing materials.