Heating of Biological Tissue in the Induction Field of VHF Portable Radio Transmitters
QUIRINO BALZANO, OSCAR GARAY, FRANCES R. STEEL · 1978
VHF portable radios cause minimal tissue heating despite strong external fields because human tissue blocks wave penetration.
Plain English Summary
Researchers tested how VHF portable radio transmitters heat human tissue using realistic phantom models of the head and body. They found that despite high field measurements near the antenna, actual tissue heating was minimal (less than 0.1°C) because the radio waves don't penetrate effectively into biological tissue. The only health risk occurs if someone places the antenna tip directly against their eye.
Why This Matters
This 1978 study provides crucial insights into how proximity to transmitting antennas affects human tissue heating. The research demonstrates that field strength measurements alone can be misleading - what matters is how much energy actually penetrates and heats biological tissue. The scientists found that VHF radio waves from handheld transmitters cause surprisingly little heating because human tissue's electrical properties cause the fields to collapse at the skin surface. This finding has important implications for understanding EMF exposure from modern devices. While portable radios operate at different frequencies than today's cell phones, the principle remains relevant: the relationship between external field strength and internal tissue effects is complex and depends heavily on frequency, antenna design, and tissue properties.
Finding
The results of the measurements performed on the head phantom have shown that a 6-W portable radio with a helical antenna held at 0.2 in from the operator's mouth causes very little heating of the simulated biological tissue (less than 0.1°C is highest temperature increase for one minute exposure). The maximum power density penetrating the dummy is less than 1 mW/cm2 in the middle forehead. No detectable temperature increase is present in the immediate eye area.
In their words
“The results of the measurements performed on the head phantom have shown that a 6-W portable radio with a helical antenna held at 0.2 in from the operator's mouth causes very little heating of the simulated biological tissue (less than 0.1°C is highest temperature increase for one minute exposure). The maximum power density penetrating the dummy is less than 1 mW/cm2 in the middle forehead. No detectable temperature increase is present in the immediate eye area.”
Figures from the Original Paper
Diagrams extracted from the original research document.
Exposure Information
Specific exposure levels were not quantified in this study.
Show BibTeX
@article{heating_of_biological_tissue_in_the_induction_field_of_vhf_portable_radio_transm_g4673,
author = {QUIRINO BALZANO and OSCAR GARAY and FRANCES R. STEEL},
title = {Heating of Biological Tissue in the Induction Field of VHF Portable Radio Transmitters},
year = {1978},
}