Environmental and auto-induced RF-EMF adult and children far-field exposure simulations between 450 MHz and 26 GHz

Abstract

Abstract Objective. Children's exposure to radio-frequency electromagnetic fields (RF-EMF) above 6 GHz lacks characterization. No study spans sub-GHz cellular bands to millimeter wave while including child phantoms. This study quantifies the specific absorption rate (SAR) and absorbed power density (APD) in two adult and two child anatomical phantoms across 15 frequencies from 450 MHz to 26 GHz. Approach. We performed 550 finite-difference time-domain (FDTD) simulations covering environmental (plane-wave) and auto-induced (beamforming) exposure. SAR and APD were computed following IEC/IEEE 62704-1 and IEC/IEEE 63195-4, respectively. The simulations included, for the first time, whole-body dosimetry at 26 GHz in child and adult phantoms, and child APD across 7-15 GHz. Results were normalized to the ICNIRP 2020 reference levels for general public exposure. Main results. Children show 1.5-1.9 times higher whole-body SAR than adults at all sub-6 GHz frequencies. A 6-year-old reaches 93% of the 80 mW/kg whole-body SAR limit at 2140 MHz, averaged over 12 plane-wave configurations, and 145% in the worst one. Whole-body SAR, not local SAR, determines compliance margins below 6 GHz. Brain SAR decreases by 96% from 450 MHz to 5.8 GHz as absorption shifts to the skin. Eye SAR drops 77-fold from 7 to 26 GHz as penetration depth falls below eyelid thickness. Under simplified MRT beamforming, psSAR10g at 3500 MHz exceeds the 2 W/kg head/torso limit for all four phantoms (131-158%). APD at 7 GHz exceeds 20 W/m^2 for a 6-year-old by 2.5%. Worst-case whole-body SAR agrees with the literature within 2%. Significance. The results identify frequency-phantom combinations where compliance margins narrow: 3500 MHz and 7 GHz under beamforming, and children near 2 GHz under environmental exposure. The organ-specific SAR data for brain, eyes, skin, and genitals support epidemiological exposure assessment and dose modeling across current and prospective wireless bands.