Toshiba VM4050 - Manual (Page 224)

2. 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.
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 normal locations in
atoms and molecules. It can permanently damage biological tissues
including DNA, the genetic material. Ionization only occurs with
Section 4: Safety Guidelines and Warranty Information
4A: Safety 213