Auto-Induced Downlink Radiofrequency Electromagnetic Field Exposure at 3.5 GHz With Focusing Near the Head

Authors: Herssens H, Thielens A

Year: 2025

Category: Bioelectromagnetics, Exposure Assessment

Journal: IEEE Access

DOI: 10.1109/ACCESS.2025.3555388

URL: https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10943211&isnumber=10820123

Abstract

Overview

This study evaluates auto-induced downlink exposure at 3.5 GHz in network scenarios where downlink RF energy is focused at user equipment (UE), creating highly localized electromagnetic field exposures near the head. The researchers compare two precoding techniques using Finite-Difference Time-Domain simulations.

Exposure Scenarios

  • UE located next to the ear (simulating phone call exposure)
  • UE positioned in front of the eyes
  • UE positioned near the nose (simulating video call exposure)

Findings

  • Exposure levels depend greatly on UE location and the precoding method applied.
  • The study uses both male and female anatomical phantoms to quantify localized specific absorption rate (SAR) values.
  • Normalization of highly focused exposures is a crucial methodological aspect. The study proposes and compares different normalization strategies in the context of international exposure guidelines.

Conclusion

  • The selection of normalization approach can lead to situations where International Commission on Non-Ionizing Radiation Protection (ICNIRP) basic restrictions are exceeded, even though reference levels may remain in compliance.
  • Ensuring compliance with reference levels alone may not safeguard against exceeding fundamental biological safety limits, highlighting the need for a precautionary stance.

🔆 Takeaway: Focused RF-EMF exposures at 3.5 GHz, especially near the head, can lead to localized SAR values that surpass international safety limits under certain conditions, reinforcing the need to review and possibly tighten exposure assessment protocols.

radiofrequency electromagnetic fields 3.5 GHz exposure assessment specific absorption rate precoding techniques ICNIRP guidelines focused exposure
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