What Is EMF | What Is RF & Microwave Radiation

Electromagnetic radiation (EMR) occurs naturally on this planet, but it is the man-made EMR that we should be aware of. Technological advances have significantly altered our electromagnetic environment. The Electromagnetic Spectrum or Frequency Spectrumranges from the natural earth magnetic field to ionizing radiation. The spectrum includes electric power transmission to operate motors and appliances, wireless systems for radio and TV transmission, cellular and wireless networks and infrared, visible and ultraviolet light. We generally differentiate EMR into these basic categories:

  • Alternating Currents (AC)
  • Direct Currents (DC)
  • Magnetic Fields
  • Electric Fields
  • Low Frequencies Fields
  • High Frequencies Fields
  • Ionizing Radiation

The electromagnetic spectrum or frequency spectrum is determined by their corresponding frequency and wavelength. The frequency is expressed in how many times the wave cycles per second and is referred to as Hertz (Hz). Alternating currents (AC) change their polarity cyclically and the polarity changes are also expressed in Hertz.

The lowest frequencies (longest wave length) are referred to as Extremely Low Frequency or ELF. Higher frequencies (shorter wave length) are referred to as Radio Frequency (RF) or Microwaves. The highest frequencies (extremely short waves) are called ionizing radiation.


The term EMF (electromagnetic fields) is used for low frequency, alternating or direct current, magnetic or electric fields. Publically, AC magnetic fields are commonly referred to as EMF. Low frequency systems are used to transmit electrical power into our buildings.

  • AC Magnetic Fields
    • Magnetic fields are created by electrical current flowing in conductors. They are associated with electrical transmission, building wiring system, transformers, motors, appliances, and power supply. The electrical power system the US runs utilizes the 60 HZ frequency, 50 Hz is used in European countries.
    • High magnetic fields can pose significant EMF health risks. Elevated magnetic fields are often caused by flaws in a buildings internal wiring system, by power lines, stray current traveling on water and gas lines, and improper grounding systems. Magnetic fields are typically measured in milliGauss (mG).
  • AC Electric Fields
    • Electric fields are created by the voltage present in the electrical system, either the building wiring or power cords. A current flow is not necessary to create an electric field. Which means a device does not have to be on to create an electric field. They can usually easily be eliminated or shielded. Electric field measurements are more complicated because the body of the tester diverts and affects the field and influences the measurement result. Electric fields are measured in Volt per meter (V/m).

RF and Microwave Radiation

High frequencies are used to transmit power and signals through the air and are wireless signal transmission systems. A multitude of systems are used, such as amplitude or frequency modulation, modulated and pulsed signals, time and code division multiplexing with new technologies constantly coming on line.

These high frequencies are used for AM and FM satellite radio, television, radar, cell towers, cell phones, cordless phones, Bluetooth, wireless computer and data transmission (WLAN, WI-FI, WiMAX) networks. The use of wireless technologies has exponentially increased over the last decade and has become a significant source of microwave radiation in buildings. Careless placement of wireless network installations in homes or offices can become a significant source of microwave radiation for occupants in the buildings.

For high frequency testing, ET&T uses a spectrum analyzer to identify the specific frequencies present and the magnitude of the signals. The strength of the field is often expressed as Power density in nanoWatt per square centimeter (nW/cm2).


Effective Electromagnetic Radiation Wifi Shield Demonstration

Direct Currents (DC)

Direct current power transmission systems have a constant flow of electric charge that does not change its polarity and therefore has a zero (0) Hz frequency. DC systems are used in batteries and low voltage lighting systems.

  • DC Magnetic Fields
    • DC magnetic fields occur naturally on this planet, the earth’s magnetic field. These static DC magnetic fields are present in regular magnets. Concerns develop when steel components in buildings become magnetized leading to the creation of magnetic fields in structures.
  • DC Electric Fields
    • DC electric fields, also referred to as Electrostatic Charge, can be created when two poorly conducting materials rub against each other. For example, a shoe sole rubbing over the synthetic carpet can create an electrostatic charge which can discharge with an electric shock. Electromagnetic charge is measured in Volts per meter (V/m) and discharge time.

Ionizing Radiation

The damaging effect of ionizing radiation in the form of X-ray, beta and gamma radiation, even in low doses, has a significant impact on human health. This has been well documented and led to threshold levels being reduced over time. Ionization radiation, if enough occurs, can be destructive to biological organisms, can cause DNA damage in individual cells and is responsible for numerous cancers. Materials high in ionizing radiation have been found in some ceramic tiles and certain stone used in countertops.

EMF/RF can assess your EMF environment, provide RF measurements and compare your building to our references values, international guidelines and standards.