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3.3 Power density (S):
Power per unit area normal (perpendicular) to the
direction of propagation, usually expressed in
2
units of Watts per square meter (W/m
) or, for
convenience, units such as mill Watts per square
2
centimeter (mW/cm
).
3.4 The characteristic of electromagnetic
fields(S):
Electromagnetic fields propagate as waves and
travel at the speed of light (C). The wavelength is
proportional to the frequency.
λ (wavelength) = C (speed of light) / f (frequency)
If the distance to the field source is less than three
wavelengths, then we are usually in the near field.
If the distance is more than three wavelengths,
the far-field conditions usually hold.
In near field conditions, the magnetic field value
cannot be calculated from the electric field value.
This meter is designed for reliable far field
measurements only.
4
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