A measurement of R F field intensities in the immediate vicinity of an F M broadcast station antenna, ORP/EAD-76-2
Tell R A · 1976
Early field measurements around FM broadcast antennas established baseline RF exposure data for our increasingly complex wireless environment.
Plain English Summary
This 1976 technical report measured radiofrequency field intensities directly around an FM broadcast station antenna. The research documented actual RF exposure levels that people might encounter near broadcast facilities. This type of field measurement data helps establish baseline exposure levels from major RF sources in our environment.
Why This Matters
This early field measurement study represents crucial foundational work in understanding RF exposure from broadcast sources. FM radio stations operate at frequencies between 88-108 MHz and can generate significant field intensities near their transmission sites. What makes this research particularly relevant today is that it documents real-world exposure levels from a time when our RF environment was far simpler than today's wireless world.
While FM broadcast antennas are typically positioned to minimize ground-level exposure, people living or working near broadcast facilities can still encounter elevated RF fields. The measurements from this 1976 study provide important baseline data for comparison with today's multi-layered RF environment, where we're simultaneously exposed to FM radio, cell towers, WiFi, and countless other wireless devices.
Finding
From an examination of the data it is clear that exposure intensities on FM broadcast towers can exceed the OSHA recommended safety level of 10 mW/cm? by more than a factor of 10.
In their words
“From an examination of the data it is clear that exposure intensities on FM broadcast towers can exceed the OSHA recommended safety level of 10 mW/cm? by more than a factor of 10.”
Figures from the Original Paper
Diagram extracted from the original research document.
Exposure Information
Specific exposure levels were not quantified in this study. Duration: about 20 minutes
Study Details
To measure electric-field energy density on the antenna tower of an FM broadcast station and determine if exposures exceed established safety standards.
Measurements were made with an electric field energy density meter, model EDM-3, designed and develo...
The highest value of energy density measured directly under the towers on the ground was 0.032 uJ/m3...
Exposure intensities on FM broadcast towers can exceed the OSHA recommended safety level of 10 mW/cm2 by more than a factor of 10. The simplest method of control appears to be to turn off the transmitter while work which requires people to be on the tower is done. Television towers are also suspected of having very high levels near the antenna since they have significantly higher powers than FM broadcast stations.
Show BibTeX
@article{a_measurement_of_r_f_field_intensities_in_the_immediate_vicinity_of_an_f_m_broad_g4986,
author = {Tell R A},
title = {A measurement of R F field intensities in the immediate vicinity of an F M broadcast station antenna, ORP/EAD-76-2},
year = {1976},
}