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U.S. Department of Health and Human Services

Radiation-Emitting Products

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Radiofrequency Background

What is radiofrequency energy (RF)?

Radiofrequency (RF) energy is another name for radio waves. It is one form of electromagnetic energy which consists of waves of electric and magnetic energy moving together (radiating) through space. The area where these waves are found is called an electromagnetic field.

Other forms of electromagnetic energy

  • gamma rays
  • x-rays
  • light.

Radio waves are created due to the movement of electrical charges in antennas. As they are created, these waves radiate away from the antenna at the speed of light.

Waves are measured by

  • the distances covered by one cycle of the wave (wavelength)
  • the number of waves that pass a certain point in one second (frequency) .

The frequency of an RF signal is usually expressed in units called hertz (Hz).

  • One Hz equals one wave per second.
  • One kilohertz (kHz) equals one thousand waves per second
  • One megahertz (MHz) equals one million waves per second
  • One gigahertz (GHz) equals one billion waves per second.

RF energy includes waves with frequencies ranging from about 3000 waves per second (3 kHz) to 300 billion waves per second (300 GHz). Microwaves are a subset of radio waves that have frequencies ranging from around 300 million waves per second (300 MHz) to three billion waves per second (3 GHz).

 How is radiofrequency energy used?

Telecommunications

  • Radio and TV broadcasting
  • Cell phones
  • Pagers
  • Cordless phones
  • Police and fire-department radios
  • Point-to-point links (microwave communication links)
  • Satellite communications

Microwave ovens

Radar

Industrial heaters and sealers

  • Mold plastic
  • Glue wood
  • Seal leather
  • Process food

Medical uses

  • Pacemaker monitoring and programming