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Measurements of Electromagnetic Fields in the Close Proximity of CB Antennas

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Paul S. Ruggera · 1979

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Government researchers measured CB antenna electromagnetic fields in 1979, establishing early protocols for RF exposure assessment.

Plain English Summary

Summary written for general audiences

This 1979 government study measured electromagnetic field levels near Citizens Band (CB) radio antennas to understand exposure patterns in close proximity to these transmitters. CB radios operate around 27 MHz and were extremely popular communication devices in the late 1970s. The research provided important baseline data for assessing RF exposure from CB antenna installations.

Why This Matters

This government research from 1979 represents an early effort to quantify RF exposure from CB radio antennas during the height of their popularity. CB radios typically operate around 27 MHz with power outputs up to 4 watts, creating localized electromagnetic fields that could affect users and nearby individuals. What makes this study particularly relevant today is how it established measurement protocols for assessing RF exposure in close proximity to transmitting antennas. The science demonstrates that understanding near-field exposures from personal communication devices has been a concern for decades, not just since cell phones emerged. While CB radios may seem antiquated, the measurement principles and exposure assessment methods developed in studies like this laid the groundwork for evaluating modern wireless devices that operate at much higher frequencies and power levels.

Finding

The data indicate that field strength limits such as those recommended in the ANSI standard C95.1-1974 can be exceeded in the vicinity of these antennas under certain circumstances.

In their words

The data indicate that field strength limits such as those recommended in the ANSI standard C95.1-1974 can be exceeded in the vicinity of these antennas under certain circumstances.

Figures from the Original Paper

Diagram extracted from the original research document.

chartPage 10 - Figure 1. Wave impedance vs. source/subject separation

Exposure Information

A logarithmic frequency spectrum from 10 Hz to 100 GHz showing where this study's 27.12 MHz exposure sits relative to common EMF sources.Where This Frequency Sits on the EMF SpectrumELFVLFLF / MFHF / VHFUHFSHFmm10 Hz100 GHzThis study: 27.12 MHzPower lines50/60 HzCell phones~1 GHzWiFi2.4 GHz5G mm28 GHzLogarithmic scale

Specific exposure levels were not quantified in this study.

Study Details

To measure electromagnetic fields in the close proximity of CB antennas and determine if field strength limits can be exceeded under certain circumstances

Measurements of near fields generated by citizen band antennas operating at 27.12 MHz were conducted...

Field strength limits such as those recommended in the ANSI standard C95.1-1974 can be exceeded in t...

The health implications of these observations are not clear at this time. The Bureau of Radiological Health is continuing investigations of this matter. Field strength limits can be exceeded in the close proximity of CB antennas under certain circumstances.

Cite This Study
Paul S. Ruggera (1979). Measurements of Electromagnetic Fields in the Close Proximity of CB Antennas.
Show BibTeX
@article{measurements_of_electromagnetic_fields_in_the_close_proximity_of_cb_antennas_g4115,
  author = {Paul S. Ruggera},
  title = {Measurements of Electromagnetic Fields in the Close Proximity of CB Antennas},
  year = {1979},
  
  
}
No DOI on file for this study.

Quick Questions About This Study

CB radios operate around 27 MHz in the high frequency (HF) band. This frequency is much lower than modern cell phones, which typically operate between 800 MHz and several GHz, but can still create measurable electromagnetic fields near the antenna.
The study aimed to measure fields in close proximity to CB antennas to establish safe distances. CB antennas can create strong localized fields within several feet of the transmitting element, particularly important for mobile installations on vehicles.
By 1979, CB radios had exploded in popularity with millions of users. Government researchers needed baseline measurements to understand RF exposure levels and develop safety guidelines for both operators and the general public near CB installations.
CB radios operate at lower frequencies than cell phones but often use higher power levels and larger antennas. The measurement techniques developed in 1970s CB studies helped establish protocols still used today for assessing RF exposure from wireless devices.
Measuring electromagnetic fields near antennas requires specialized equipment and careful positioning to avoid interference. In 1979, field measurement technology was less sophisticated, making accurate near-field assessments more difficult than with today's digital instruments.