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Measurements of Electromagnetic Fields in the Close Proximity of CB Antennas

Bioeffects Seen

Paul S. Ruggera · 1979

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Government researchers were measuring RF exposure from personal communication devices decades before cell phones became widespread.

Plain English Summary

Summary written for general audiences

This 1979 government study measured electromagnetic field levels near CB (Citizens Band) radio antennas to understand radiation exposure in close proximity to these transmitters. The research focused on documenting actual field strengths that CB radio operators and nearby individuals might encounter during typical use.

Why This Matters

This early government research represents an important milestone in understanding RF exposure from personal communication devices. CB radios, popular in the 1970s, transmitted at power levels similar to today's cell phones but used different frequencies and antenna configurations. What makes this study significant is its focus on 'close proximity' measurements - the kind of exposure patterns we now recognize as critical for health assessment. The reality is that CB operators often positioned antennas on vehicles or homes, creating potential exposure scenarios that parallel today's concerns about cell towers and rooftop installations. While we lack the specific findings, government agencies were clearly recognizing the need to quantify RF exposure levels from consumer communication devices nearly half a century ago.

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.

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_g4113,
  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 antennas operated in the 27 MHz frequency band and could produce significant electromagnetic fields within several feet of the antenna, especially during transmission when operators pressed the microphone button.
CB operators sat directly next to their radios while transmitting, and mobile antennas were often mounted on vehicle roofs just feet above occupants, creating close-proximity exposure scenarios.
By 1979, millions of Americans used CB radios, and government agencies needed to understand potential RF exposure levels from these popular communication devices to establish safety guidelines.
CB radios typically transmitted at 4-5 watts maximum power, similar to early cell phones, but used different frequencies and antenna designs that affected exposure patterns.
Unlike broadcast antennas located far away, CB antennas were positioned very close to users - on dashboards, rooftops, or handheld units - creating direct near-field exposure scenarios.