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Consumer Information on Wireless Phones
(The following information comes from a consumer information Website jointly
sponsored by the U.S. Food and Drug Administration (FDA) and the Federal
Communications Commission (FCC), entitled "Cell Phone Facts: Consumer Information
on Wireless Phones."The information reproduced herein is dated July 29, 2003. For
further updates, please visit the Website: http://www.fda.gov/cellphones/qa.html.)
What is radiofrequency energy (RF)?
Radiofrequency (RF) energy is another name for radio waves. It is one form of
electromagnetic energy that makes up the electromagnetic spectrum. Some of the
other forms of energy in the electromagnetic spectrum are gamma rays, x-rays and
light. Electromagnetic energy (or electromagnetic radiation) 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.
Radio waves are created due to the movement of electrical charges in antennas. As
they are created, these waves radiate away from the antenna. All electromagnetic
waves travel at the speed of light. The major differences between the different types
of waves are the distances covered by one cycle of the wave and the number of waves
that pass a certain point during a set time period. The wavelength is the distance
covered by one cycle of a wave. The frequency is the number of waves passing a given
point in one second. For any electromagnetic wave, the wavelength multiplied by
the frequency equals the speed of light. 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, and 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?
Probably the most important use of RF energy is for telecommunications. Radio and
TV broadcasting, wireless phones, pagers, cordless phones, police and fire
department radios, point-to-point links and satellite communications all rely on
RF energy.
Other uses of RF energy include microwave ovens, radar, industrial heaters and
sealers, and medical treatments. RF energy, especially at microwave frequencies, can
heat water. Since most food has a high water content, microwaves can cook food
quickly. Radar relies on RF energy to track cars and airplanes as well as for military
applications. Industrial heaters and sealers use RF energy to mold plastic materials,
glue wood products, seal leather items such as shoes and pocketbooks, and process
food. Medical uses of RF energy include pacemaker monitoring and programming.
Section 4A: Safety
147
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