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Section 4: Safety Guidelines and Warranty Information
4A: Safety 110
2. How is radiofrequency energy used?
Probably the most important use of RF energy is for telecommu-
nications. 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.
3. How is radiofrequency radiation measured?
RF waves and RF fields have both electrical and magnetic
components. It is often convenient to express the strength of the
RF field in terms of each component. For example, the unit "volts
per meter" (V/m) is used to measure the electric field strength,
and the unit "amperes per meter" (A/m) is used to express the
magnetic field strength. Another common way to characterize an
RF field is by means of the power density. Power density is
defined as power per unit area. For example, power density can
be expressed in terms of milliwatts (one thousandth of a watt)
per square centimeter (mW/cm2 or microwatts (one millionth of
a watt) per square centimeter (µW/cm2).
The quantity used to measure how much RF energy is actually
absorbed by the body is called the Specific Absorption Rate or
SAR. The SAR is a measure of the rate of absorption of RF
energy. It is usually expressed in units of watts per kilogram
(W/kg) or milliwatts per gram (mW/g).
4. What biological effects can be caused by RF energy?
The biological effects of radiofrequency energy should not
be confused with the effects from other types of
electromagnetic energy.
Very high levels of electromagnetic energy, such as is found in
X-rays and gamma rays can ionize biological tissues. Ionization
is a process where electrons are stripped away from their