ELF electric and magnetic field measurement methods

The authors surveys the instrumentation, calibration procedures, measurement techniques, and standards which can be used to characterize extremely low frequency (ELF) electric and magnetic fields. While the focus is on power frequency and power frequency harmonic fields, the measurement methods discussed are appropriate in principle for other ELF frequencies. Following a brief description of electric and magnetic fields near AC power lines, the types of field meters and their principles of operation are surveyed. Consideration is given to features necessary in the design of instrumentation to adequately characterize electric and magnetic fields with harmonics and fields which are highly nonuniform. Calibration techniques for magnetic field meters which are used to characterize fields over the dynamic range of a few nanotesla to about a millitesla are discussed. Measurement techniques in various environments as well as their limitations are also discussed, and examples of measurement results in several different environments are presented