ETS-Lindgren 3160 Series, Руководство пользователя

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E
QUATION
2
dB(mW /m
2
) = dB(
μ
V/m)-115.8
The constant in this equation is obtained by considering the
Poynting vector which relates the power density in (W/m
2
) to the
electric field strength in (V/m) by:
P =
E
2
η
Where
η
is the free space characteristic impedance equal to 120
π
Ω .
Transforming the previous questions to decibels and using the
appropriate conversion factors to convert dB(W/m
2
) to dB(mW/m
2
) for
power density and dB(V/m) to dB(µV/m) for the electric field, the
constant becomes:
30 120 10 120 115 8
10
− − = −
log ( ) .
π
E
QUATION
3
dB(
μ
V/m) = dB(
μ
V) + AF
E
QUATION
4
V/m = 10
dB ( V/m)-120
μ
20
E
QUATION
5
dB (
μ
A/m) = dB(
μ
V/m) - 51.5
The magnetic field strength is related to the electric field strength via
the characteristic impedance of free space. When the transformation is
made to decibels, the constant becomes:
20 120 51 5
10
log ( ) .
π
=
Radiated Emissions Measurements |
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