Nationwide EMF-EMI Site Surveys

ELEXANA provides EMI and EMF Testing, Diagnostics, Analysis, Troubleshooting, Trend Data Logging, Surveys, Assessments, and Mitigation Consulting.

We use ISO 17025-certified, calibrated instruments for all high-risk measurements, assured accuracy, and replicability, with traceable official reports. Our EMI/EMF survey measurements include GPS coordinates (outdoors only) and time stamps.

We are:

A Member of the Electromagnetic Compliance Society of the IEEE

A Member of the IEEE New York Chapter

OSHA-certified

NFPA® 70E Certified Grounding and Bonding Testing

ANSI/AEMC Engineered Trained

A Member of the Bioelectromagnetics Society

A Member of the NFPA® National Fire Protection Association

D-U-N-S Registered

A Member of the E-Verified Program

Vetted and Approved by Homeland Security and the FBI

HIPAA Compliant

Why Be Concerned About EMI?

Electromagnetic interference (EMI) causes latency, malfunction, and sluggish performance to fine electronics such as computers, medical devices and equipment, pacemakers, financial trading platforms, graphic software, recording equipment, etc.

With the exponential increase of wireless technologies in New York City, EMI has become a common vernacular. Line noise, harmonic transients, dirty electricity, RFI (radio frequency interference), and electromagnetic coupling are synonyms.

How Do You Know It’s EMI?

An easy way to tell if you have an EMI issue is to look for the presence of:

Unwanted screen images, patterns, static, or artifacts.
Overheating of any metal enclosures. Are enclosures very hot to the touch?
Motor failures from overheating.
Fuses blowing for no apparent reason.
Static or interference on sound or voice communication.
The electronic equipment is shutting down for no apparent reason.
The computer malfunctions or locks up.
Flickering of fluorescent or LED lights.
Blinking incandescent lights.

Electromagnetic Interference (EMI) occurs when an unintended electromagnetic force (EMF) couples onto a conductor.

Four Types of Electromagnetic Coupling

1. Conductive Coupling occurs when the coupling path between the source and the receptor forms direct electrical contact with a conducting body,

An example of Conductive Coupling occurs when a municipal water service pipe has a reverse neutral stray current, and the lightning protection system ground wire connected to it conducts this neutral current back onto the neutral bus of an electrical panel. Line EMI or signal-to-noise can occur from the same or opposite directions.

We call this common impedance when the signal-to-noise ratio appears in phase in the same direction on both conductors.
We call this differential impedance when the signal-to-noise ratio appears out of phase, in the opposite direction on both conductors.

2. Inductive Coupling occurs when a strong electromotive force intersects an electrical conductor within a magnetic field, causing the original magnetic field to become distorted. James Clerk Maxwell, who preceded Albert Einstein, mathematically described this process as "Faraday's Law of Induction." An example of inductive coupling is when an underground power line runs close enough to a water pipe that the pipe acquires leakage current.

3. Capacitive Coupling occurs when two fluctuating electrical fields co-exist between two adjacent conductors, thereby inducing a change in voltage on the receiving conductor receptor. Capacitive Coupling is among the most intriguing and challenging for the new student. We see this occurring when we turn off the branch circuit in a room and register that the electric field has become stronger. This happens because the electrician had strung wires in parallel from different branch circuits.

4. Radiative Coupling occurs when the distance exceeds one wavelength between the source point and the receptor. The source point emits or radiates an electromotive force across space that a conductor receives. An example is a cell transmitter sending signals that inadvertently couple onto your equipment’s wiring. This is termed “unintentional coupling.”

Welding equipment can stress pacemaker function.

The human exposure reasons for testing can range from testing for site compatibility for an employee's pacemaker or defibrillator to determine if it will function throughout the day without suffering interference issues, to employees claiming that their work environment is causing them harm, or has caused their illness.

A medical device manufacturer will have extensively stress-tested their products for EMI immunity before going to market, ensuring their relative safety. Nevertheless, severe electromagnetic environmental stress will cause any electronic device to fail. The patient's doctor can make EMI threshold levels of a biomedical device available; then you can call on Elexana to test your facility.

Site testing must be detailed and thorough. Pacemakers and other biomedical implants require specific, certified, calibrated equipment. The surveyor needs an OSHA certification and must have experience working in industrial sites. The company must carry General Liability and Professional Liability Insurance.

If an employee complains about the EMI or EMF levels at the workplace, the situation is somewhat different for the EMF Consultant. Often, we see that the employee has purchased a meter on the internet and finds that their measurements exceed the specific standards. However, there are many problems with these types of employee measurements.

First, these meters are usually uncalibrated and skew readings towards an exaggerated high side. Also, inexpensive meters made for amateurs are prone to spurs or internal circuitry overload, often presenting false peak readings to the high side. Another mistake I see "professionals" make in measuring technique is placing a meter too close to the source. We have all seen the amateur put the RF meter to the cell phone or wifi or a Trifield EMF meter to an electrical panel. (It is one thing to do this for a photo-op, but another for a survey.)

Most meters cannot be measured at the extreme of the near field. Indeed, no RF meters can be measured accurately in the near field. A third mistake I see amateurs and some "professionals" make is that they do not identify the correct energy source; instead, they measure the correct energy but identify the wrong energy cause.

So, surveys are measured from a source point, and typical industrial surveys are measured on a grid or a straight line. Often, a factory will have support columns marking each section. These marked sections make it easy to document a grid survey. Sometimes, a GPS enhances the measuring and documentation process. Other times, using our NFA 1000s, we can data log and map simultaneously. (See the chart.) (Note: Calibration of the NFA1000 takes place in Germany.)

Grid surveys can be helpful. After identifying elevated levels, an overlap survey will be added to determine the correct sources and proper mitigation.

EMI Services

Equipment Interference Issues and Concerns: On-site EMI troubleshooting, diagnostics, and attenuation for laboratory and medical equipment, metal detectors, surveillance equipment, autonomous vehicles, trading platforms, broadcast, video, and music recording
Industrial EMI diagnostics and analysis for AIC - Artificial Intelligence Compatibility™
Research laboratory EMI diagnostics and analysis for SEM/TEM on-site electromagnetic compliance to specifications
Medical laboratory EMI diagnostics and analysis for MRI, NMR, EKG, and EEG equipment on-site compliance
Electromagnetic interference (EMI) attenuation for peak electronic, computer performance, and information technology equipment
RFI, E-Field, B-Field, GIC, H-Field, and AC magnetic shielding design
Architectural and engineering EMI/RFI consultations
EMC/EMI Pre-Compliance testing at your facility
Long-term data logging and RF masking

What are the Differences Between EMF, EMI, and EM Surveys?

This article is about the differences between the three types of surveys involving electromagnetic radiation and the distinct purposes of each. These three types of surveys are:

1. Electromagnetic Field Radiation Surveys, EMF, or EMR;

2. Electromagnetic Interference Surveys, EMI, and

3. Electromagnetic Surveys, EM. Some of the tools used for each type will be discussed.

Electromagnetic Field Radiation Survey (EMF Radiation Survey)

These surveys assess the electromagnetic radiation in the environment at a specified location.

The primary purpose of an EMF Survey is to assess human or equipment exposure to electromagnetic field radiation from power lines, cell towers, Wi-Fi, microwave ovens, etc.
EMF Surveys are used for occupational safety, regulatory compliance, health impact studies, and electronic equipment shielding. This shielding is usually for either radio frequency or AC magnetic field radiation from a source such as a transformer, electrical switch gear, conduit, or electrical closets.
Generally, EMF Surveys are conducted using portable meters that measure the strength of existing EM fields across various frequency bands. A good assessment covers the entire frequency range of the standard applied or a project’s requirements.
The tools often used for EMF Surveys are listed below.

Electromagnetic Interference (EMI) Survey

An electromagnetic interference EMI survey is a scientific assessment of the unintended conductive and radiative emissions that may interfere with the functioning of electronic devices or systems.

The essential measurements needed for an EMI assessment are:

1. Conducted emissions are harmonic transients, signal noise, traveling along cables, traces, power lines, etc.)

2. Radiated emissions are electromagnetic energies traveling through the air.

Subsets of these emissions are:

A. Inductive Coupling is magnetic field energy generated by current, and the transients are coupled with the magnetic field’s fundamental. In the case of an AC magnetic field in the USA, this fundamental is 60 Hertz. In Europe, the fundamental is 50 Hertz.

B. Capacitive Coupling is electric field energy generated by a voltage, potential, and the transients are coupled with the electric field’s fundamental. An AC electric field in the USA has a fundamental frequency of 60 Hertz. In Europe, the fundamental is 50 Hertz.

Common reasons why someone would want an EMI survey are:

Aerospace and defense systems (shielding effectiveness).
Medical devices (ensuring hospital equipment is restored to normal function).
Industrial or communication sites (preventing signal loss or distortion).

Electromagnetic Field (EMF) Radiation Survey

An EMF survey measures the strength and presence of various electromagnetic field radiation in an environment, typically to assess human exposure levels. In the US, guideline levels for human exposure are found in Bulletin OET-65.

An EMF survey aims to ensure compliance with health and safety regulations related to EMF exposure, not necessarily to address equipment interference.

Essential measurements and their units are:

Electric fields (V/m: Voltage per meter).
Magnetic fields (A/m, µT, or mG: Amperes per meter, microTeslas, or milliGauss).
Power density (W/m², W/cm²: Watts per square meter or square centimeter across various frequency bands).

The general applications for an EMF survey are:

Assessing radiation from power lines, cellular towers, Wi-Fi routers, and electrical wiring and equipment.
Workplace or residential safety evaluations.
Environmental impact assessments.

Electromagnetic Survey (EM Survey)

EM surveys are used in geophysics and subsurface exploration.

The reason for conducting an EM survey is to detect variations in the ground’s electrical conductivity and magnetic permeability.
These surveys are used for mineral exploration, groundwater mapping, environmental site assessment, and locating buried objects.
Instruments send or inject electromagnetic signals into the ground; the response (secondary fields) is measured to infer what’s underground.
Time-domain EM systems and frequency-domain EM instruments are used for EM surveys.

The main difference among the three types of surveys is:

EMF surveys focus on whether electromagnetic fields affect human health and safety.
EMI surveys focus on whether electromagnetic emissions may disrupt equipment and systems.
EM surveys focus on locating what is below Earth’s surface.

The Tools Used for Different Surveys

While electromagnetic interference (EMI) surveys, electromagnetic field (EMF) radiation surveys, and electromagnetic surveys (EM) deal with electromagnetic phenomena, they have different goals and use other tools.

Electromagnetic Field (EMF) Radiation Survey

The aim is to measure electromagnetic field levels to assess human exposure or environmental impact, often for health, safety, or regulatory compliance (e.g., near cell towers, power lines, or industrial equipment).
The standard equipment used for measuring EMF is:

Broadband EMF meters — handheld devices that measure field strength across a wide frequency range, usually giving total field strength (V/m, A/m, W/m²).
Gaussmeters or magnetometers — to measure static or low-frequency magnetic fields.
Electric field meters — to measure static or low-frequency electric fields.
Isotropic probes — sensors that capture field strength from all directions, 360º. These are essential for assessing human exposure.
Personal EMF dosimeters are generally wearable devices for logging individual exposure over time.
These tools are adept at measuring field strength levels, time-averaged exposure, and safety compliance with limits set by agencies like the FCC, ICNIRP, IEEE, or national health guidelines.

Electromagnetic Interference (EMI) Survey

The aim is to identify, locate, and quantify sources of electromagnetic noise that interfere with the operation of electronic devices or systems (e.g., computers, radios, avionics, medical equipment). (Please note: At Elexana, we take this one more step to troubleshoot for optimal solutions that further suit our clients’ needs and budget. Often, the survey will include the solutions.
Typical Tools:

Spectrum analyzers — measure signal levels over various frequency bands and help detect interference sources.
EMI receivers are specialized equipment that measure conducted and radiated emissions. They are compliant with standards (like CISPR and MIL-STD).
Near-field probes — handheld probes (magnetic and electric) for local “sniffing” near circuit boards or cables.
Current clamps are used to measure noise on power or signal lines.
Anechoic chambers are shielded rooms designed to prevent outside EM signals and reflections.
Portable TEM cells are impedance-balanced transverse electromagnetic enclosures, usually within a Faraday cage, that serve a similar purpose to an anechoic chamber.

An EMI survey focuses on specific frequency bands, transient signals, narrowband or broadband interference, and compliance with regulatory limits (e.g., FCC, CISPR).

Electromagnetic (EM) Survey

Time-domain electromagnetic (TDEM) Systems- Inject pulsed EM fields into the ground and measure transient responses over time.
Specific tools: Geonics PROTEM, Zonge GDP-32, ABEM WalkTEM
Frequency-Domain Electromagnetic (FDEM) Systems - Transmit continuous EM waves at multiple frequencies, measure ground conductivity.
Tools: Geonics EM31, EM34, EM38, DualEM-421, GEM-2 by Geophex
Controlled-Source Audio Magnetotellurics (CSAMT) - Use an artificial EM source to probe deeper structures, combining electric and magnetic field data.
Tools: Zonge CSAMT, Phoenix Geophysics systems
Magnetotelluric (MT) Systems—These passive systems use natural EM signals from lightning and solar activity to probe the deep earth.
Tools: Phoenix MTU-5A, Quantec Spartan MT
Ground Conductivity Meters: Handheld or portable devices for shallow surveys, often for environmental or agricultural work.
Tools: Geonics EM38, EM31; CMD Explorer
Loop and Coil Sensors (Transmitter/Receiver Coils) - Transmit and receive EM signals; vary in size for shallow or deep penetration.
Tools: Custom loop setups with induction coils.
Resistivity and Induced Polarization (IP) Systems. - While not strictly EM, it is often combined to measure resistivity and chargeability alongside EM surveys,
Tools: IRIS Syscal Pro, ABEM Terrameter
Data Logging and Processing Software: - Specialized software to model subsurface conductivity from collected EM data.
Tools: EMIGMA, Maxwell, Res2DInv, Aarhus Workbench.

Elexana LLC is recognized globally as a top-tier Electromagnetic Interference (EMI) site survey provider due to its comprehensive approach, technical expertise, and commitment to client-centric solutions. Here's an overview of the factors contributing to its esteemed reputation.