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A New Near-Zone Electric Field-Strength Meter

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Frank M. Greene · 1966

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Accurate near-zone electric field measurement tools developed in 1966 laid groundwork for modern EMF exposure assessment.

Plain English Summary

Summary written for general audiences

This 1966 technical report describes the development of a new instrument for measuring electric field strength in the near-zone, the area close to EMF sources where field patterns are complex and measurements are most critical. The research focused on creating more accurate measurement tools for electromagnetic fields at close distances from transmitting equipment.

Why This Matters

This technical development from 1966 represents an important milestone in our ability to accurately measure electromagnetic field exposure. Near-zone measurements are particularly crucial because this is where field strengths are highest and most variable - exactly where people often find themselves when using electronic devices or living near transmission equipment. The reality is that without precise measurement tools like the one described in this report, we cannot properly assess EMF exposure levels or establish meaningful safety standards. What this means for you is that the foundation for modern EMF measurement techniques traces back to pioneering work like this, which enabled researchers to begin documenting the field strengths we encounter in our daily lives from sources ranging from household appliances to broadcast antennas.

Exposure Information

A logarithmic frequency spectrum from 10 Hz to 100 GHz showing where this study's 150 kHz to 30 MHz exposure sits relative to common EMF sources.Where This Frequency Sits on the EMF SpectrumELFVLFLF / MFHF / VHFUHFSHFmm10 Hz100 GHzThis study: 150 kHz to 30 MHzPower lines50/60 HzCell phones~1 GHzWiFi2.4 GHz5G mm28 GHzLogarithmic scale

Specific exposure levels were not quantified in this study.

Study Details

The instrument is capable of measuring both the magnitude and direction of elliptically polarized CW electric fields having strengths in the range from 0.1 to 1000 volts per meter at frequencies from 150 kHz to 30 MHz. This represents one step in the effort to develop accurate and meaningful measuring and calibrating instrumentation, for use in evaluating hazards of electromagnetic radiation to electro-explosive ordnance devices.

The design of the NBS meters is based on the use of a novel form of telemetry, employing a completel...

The completed NBS near-zone TRF field-strength meters underwent extensive acceptance tests at the U....

The design and performance of the NBS meters are discussed in some detail. The use of a high-loss, parallel-conductor, balanced transmission line of this type has been found to reduce the perturbation of the surrounding field by more than two orders of magnitude below that existing in the case of a copper line. This renders any effect of the line on the field wholly negligible in most instances. The NBS TRF meters showed the capability of measuring electric-field strengths without difficulty over the entire range from 0.1 to 1000 volts per meter (RMS).

Cite This Study
Frank M. Greene (1966). A New Near-Zone Electric Field-Strength Meter.
Show BibTeX
@article{a_new_near_zone_electric_field_strength_meter_g7017,
  author = {Frank M. Greene},
  title = {A New Near-Zone Electric Field-Strength Meter},
  year = {1966},
  
  
}
No DOI on file for this study.

Quick Questions About This Study

Near-zone measurement captures electric field strength close to EMF sources, where fields are strongest and most complex. This region extends roughly one wavelength from the source, making accurate measurement technically challenging but critically important for exposure assessment.
The 1960s saw rapid expansion of radio, television, and radar systems, creating need for better measurement tools. Existing instruments couldn't accurately measure the complex field patterns that occur close to transmitting equipment, limiting safety assessments.
Near-zone fields change rapidly with distance and have complex patterns, while far-zone fields are more uniform and predictable. Near-zone measurements require specialized instruments because standard far-field assumptions don't apply in this region.
Electronic components were less sophisticated, and near-zone fields create measurement artifacts due to instrument interference with the field being measured. Developing meters that didn't distort the very fields they were measuring required innovative engineering approaches.
Accurate field measurement is fundamental to all EMF health research. Without reliable measurement tools like those developed in this era, researchers couldn't establish dose-response relationships or create meaningful exposure standards for the devices we use today.