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An Electromagnetic Field Radiation Test is the scientific measurement of an energy source’s electron particle spectral lines of force, including its potential (V/m = Volts-per-meter) and current (A/m = Amperes-per-meter.) This measurement often includes the power density (flux: measured in T = Teslas or G = Gauss) wave vector magnitude, amplitude, polarity, frequency band, the field’s dimensions, shape, and direction while considering the distance from the source with time and magnitude derivatives.
The energy of an electromagnetic field increases proportionally with the increased frequency (Planck’s Law.) Beyond the EMC (Electromagnetic Compatibility) Test Lab, the ambient electromagnetic environment will determine if the consultant needs to consider other variables such as transconductance, co-signaling, multi-path interference, rate of intermodulation, temperature, humidity, time of day, season, as well as the space from the source to the measuring instrument, i.e., air, liquid, solid, or mixed medium.
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Compensation is necessary for the measuring tools' frequency response and noise floor. Except for the best instruments, spurious events (spikes created within the internals of the instrument) caused by internal voltage fluctuations, polarity shifting, and electromagnetic interference can skew measurements. Spurious events need to be identified and omitted from the findings, and the instrument’s deviation of error should always be factored in with any measurement. These factors are why all measurements need to be verified by taking multiple readings.
A Rule of Thumb is that the greater the radius from the energy source, the weaker the field's strength. (See Footnote 1.) This rule of thumb can deviate with reflection rates and dense multipath co-signaling. The rate of frequency fluctuation and phase noise or jitter can also contribute to the assessment equation.
In the real world of On-site EMF Testing, where we few EMI Consultants journey each day, beyond the in vitro studies and EMC rooms to enter into realms that no laboratory EMC technician or scientist has yet to study, we determine real-life electromagnetic compatibility and immunity. This is the world of Elexana.
An Electromagnetic Field Radiation Test is essential to most Electromagnetic Interference (EMI) assessments. The essential purpose of any EMF Testing is to determine whether electromagnetic fields may cause interference to your electrical systems, equipment, or worker safety. In other words, we conduct EMF testing to accrue data.
We measure and assess various orders or bandwidths of the EMF spectrum. The EMF spectrum ranges from 0 Hertz DC static and ULF (Ultra-Low Frequencies) and ELF (Extremely Low-Frequencies) AC Electromagnetic Fields, which includes the 60 Hertz frequency of North American electricity to High-Frequency (HF) Microwave Communication and Information Signals in the Gigahertz Frequency range.
Determining the transient harmonic frequencies and measuring amplitude on the electrical wiring and the RF harmonics coupled to the electroquasistatic or magnetoquasistatic fields should always be included.
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EMF Testing can include the measuring and assessing of light, both human-made and natural. Light is an EMF not often mentioned, as well as nuclear radiation (ionizing radiation.) Nuclear ionizing radiation testing measures radon, uranium, thorium, cesium, plutonium, and x-ray (alpha, beta, and gamma) radiation levels for time exposure or dosage level. (See Footnote 3.)
To help you understand more about what is involved in a typical EMF testing of a facility, here is a list of what you could expect from a professional EMF Testing Service:
Stray currents and Voltage can enter your facility via the water service, gas service, coaxial internet service lines, or HVAC system. We measure current in amperes and as magnetic flux density or voltage in millivolts (mV) as electric flux. (Sometimes, we are requested to measure in A/m, amperes-per-meter.) Be sure your consultant can provide solutions compliant to the National Electric Code, NEC.
Complete Grounding System assessment check and measuring in mV, amperes, and fundamental frequencies are often not 60 Hertz. This check is for two tests: the EGC Equipment Ground Conductor System and the Overload Lightning Protection System.
AC Magnetic Fields, both indoors and outdoors, must be measured. We identify and isolate the size, shape, coupled frequency bands, general velocity, and co-signaling fields. We identify source points, assess them, and then propose good, better solutions.
AC Magnetic emissions from your equipment and other sources such as power lines, electrical conduits, wiring errors, etc. The consultant should be qualified to identify wiring errors and instruct your electrician on how to fix them.
AC Electric Fields, measured in V/m, include all E-fields emitted by ungrounded or poorly grounded equipment, unshielded electrical cabling, and poorly grounded electrical distribution lines. This can account for capacitive coupling. Read the article → ◉
DC Magnetic Fields are measured with an industrial transverse probe or a triaxial sensor array. DC magnetism interferes with electron scanners, medical equipment, superconductors, and more. Geomagnetic foundation stress fractures can present an issue in some locations.
DC Electrostatic Fields, measured for source-point identification. (We measure this in V/m for commercial interference applications and surface voltage for those with pacemakers and heart conditions.) Be sure to receive a solution plan.
Epidermal Voltage, measured at the workstations to determine and remediate source points. Much of this work is an assessment. (This is a special request line-item service.)
Electromagnetic Interference, EMI, often occurs on the electrical line with transient frequencies above 1.5 kHz, sometimes called line noise. Occasionally, the frequency of the fundamental is not 60 Hz. Further, considering ambient EMI is essential. (See Footnote 2.)
Radio Frequencies in the real-world present an incident wave, resultant waves from third-order intercepts, reflection, refraction, diffraction, and the often overlooked standing waves. At Elexana, we measure RF/RFI in 3-D with a spectrum analyzer in dBm, Watts (W), Voltage (V), and Amperage (A) of both pulsed and non-pulsed emissions. Measuring RFI in µW/m² with our hand-held analyzers facilitates finding and isolating source-points directionality using a LogPer antenna (and a HyperLog antenna, if required.) The consultant should consider much more than just the power density levels, for example, reflection rate, coherence, multi-path interference, and more. Only measuring peak levels does NOT tell the whole story for providing the best RF solutions.
Impedance and Isolation verifications are always necessary if you plan to install a new MRI or X-ray room, research laboratory, aerospace lab, etc.
Bonding Testing with resistance measurements on the system ground to supplement current readings and support findings for proper solutions.
Earth Ground Soil Resistivity Tests are a good idea every few years because the electromagnetic environment continually changes. Your railway system or facility may be properly grounded, but the Earth it is grounded on may have lost its integrity. Another instance is when a third-party vendor may not have placed your ground rods or rings at the proper depth. We conduct a soil resistivity test with a state-of-the-art 4-point ground rod Wenner Test upon request for the correct resistance on your grounding system. We can then calculate the proper depth for your ground rods. Whatever our consultant locates has an appropriate solution compliant with the NEC.
Baseline Testing: A full and final conclusive EMF assessment of all emissions from outside the facility versus those produced within. Make sure the consultant provides clear solutions. Only recommending that you get some distance from a source point is never a professional solution.
EMF Testing an entire facility, especially near and around the DUT (Device Under Test) or EUT (Equipment Under Test), can often present information on why EMI is causing malfunctioning.
EMF Testing of a prospective investment property is always recommended to help determine the potential compatibility of the Earth's ground and the ambient EMF with your facility’s electrical systems, equipment, and worker safety.
Photo: of James Finn (Compliant with DOJ requirements.)
All pages on this website are written by James Finn, EMRS, Principal EMI Consultant at Elexana LLC
Footnote 1. Usually, the Inverse Square Law, first postulated by Ismaël Boulliau, applies for determining the rate of diminishing magnitude: I = Ø • (1/r²)
I = Intensity or in modern terms, magnetic flux density. Ø = measured magnetic flux. r = radius, distance from a center-point, or for complex vector sum calculations, “r” is the hypotenuse.
Footnote 2. I have invented new methods for testing EMI harmonic transients (S/N) within a facility. These systems create increased accuracy of our assessments, providing deeper insights into challenged immunity.
Footnote 3. Professional nuclear radiation testing requires ANSI-approved personal protective equipment (PPE.) Testing also requires specific licensing and insurance. Be sure to receive a PDF of the company’s license and their certificate of insurance with this service listed, prior to entering contractual agreements.
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Read: ‘What is the difference between EMF and EMR Testing?’