A Study on EMF Exposure Assessments With Different Metrics for User Equipment Antennas at 6 and 10 GHz

User equipment (UE) needs to comply with regulations limiting the exposure of the human body to electromagnetic fields (EMFs). In this article, three exposure metrics, including specific absorption rate (SAR), incident power density (IPD), and absorbed power density (APD), are quantified for different UE antenna designs. The exposure ratios of the metrics are quantified according to the relevant EMF limit values. The investigations are performed at or close to the transition frequency between different exposure metrics: the range 6-10 GHz being of research interest and currently attracting attention for emerging mobile technologies. The study demonstrates that the IPD does not correlate well with the APD, within the investigated frequency region, when the reactive near-field of the antenna is of interest. This is in accordance with the International Commission on Nonionizing Radiation Protection 2020 guidelines meaning that the APD should be used for compliance purposes. For validation purposes, prototypes are fabricated, and SAR and IPD are measured. The average difference between the numerical and experimental results is 0.4 dB for SAR and 0.9 dB for the IPD, meaning that good agreement between simulations and measurements is obtained.