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A SYSTEM FOR DETERMINING THE RADIOFREQUENCY ABSORPTION COEFFICIENT OF THE HUMAN BODY IN THE HIGH FREQUENCY BAND

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S.C. Kashyap, F.R. Hunt · 1977

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This 1977 study established precise methods for measuring human EMF absorption that remain foundational to modern safety assessments.

Plain English Summary

Summary written for general audiences

Researchers in 1977 built a sophisticated laboratory system to precisely measure how much radiofrequency energy the human body absorbs when exposed to 10-26 MHz electromagnetic radiation. The system could simulate both free-space and grounded conditions with exceptional precision of ± 0.05% in power absorption measurements. This early work established important methods for quantifying human EMF exposure that remain relevant today.

Why This Matters

This 1977 study represents a pivotal moment in EMF research when scientists first developed precise methods to measure how much radiofrequency energy our bodies actually absorb. The researchers achieved remarkable measurement precision of ± 0.05%, establishing gold-standard techniques that influence how we assess EMF exposure today. What makes this particularly significant is the frequency range studied: 10-26 MHz covers shortwave radio broadcasts and some industrial heating applications that people encounter daily.

The reality is that this foundational work helped establish the scientific framework we still use to evaluate EMF safety limits. While the technology has evolved dramatically since 1977, the basic physics of how electromagnetic fields interact with human tissue remains the same. Understanding absorption coefficients at these frequencies provides crucial baseline data for assessing exposure from modern wireless devices operating at higher frequencies.

Exposure Information

Specific exposure levels were not quantified in this study.

Cite This Study
S.C. Kashyap, F.R. Hunt (1977). A SYSTEM FOR DETERMINING THE RADIOFREQUENCY ABSORPTION COEFFICIENT OF THE HUMAN BODY IN THE HIGH FREQUENCY BAND.
Show BibTeX
@article{a_system_for_determining_the_radiofrequency_absorption_coefficient_of_the_human__g5369,
  author = {S.C. Kashyap and F.R. Hunt},
  title = {A SYSTEM FOR DETERMINING THE RADIOFREQUENCY ABSORPTION COEFFICIENT OF THE HUMAN BODY IN THE HIGH FREQUENCY BAND},
  year = {1977},
  
  
}

Quick Questions About This Study

The researchers tested radiofrequency absorption in the 10-26 MHz range, which covers shortwave radio broadcasts and some industrial heating applications. This frequency band was chosen to study fundamental EMF absorption patterns in human tissue.
The measurement system achieved exceptional precision of ± 0.05% of incident power (± 0.002 dB in insertion loss) after computer averaging. This level of accuracy was remarkable for 1977 and established high standards for EMF research.
The TEM (transverse electromagnetic) cell was a massive rectangular chamber measuring 12.2 m long × 7.3 m wide × 6.1 m high. Subjects were positioned between the vertical septum and outer wall to simulate controlled EMF exposure conditions.
Yes, from 20-30 MHz the researchers found that traveling wave modes and resonant standing wave patterns altered the field distribution. The largest field gradient showed 50-60% variation across the 1.8 meter length of a human subject.
The system could simulate both free-space and grounded conditions, allowing researchers to study how EMF absorption changes based on environmental factors. This capability was crucial for understanding real-world exposure scenarios beyond laboratory settings.