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INSTRUCTION MANUAL
AL-RE101
LOOP ANTENNA
SECTI ON 5
-
ANTENNA THEORY
1912 1 E l T o ro R d
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Si l vera do, Ca lifo rni a 9 26 76
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(9 49) 459 -96 00
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co m-p o wer. com
Rev101617
EXAMPLE CALCULATION #3
In the following example,
Equation (4)
is solved for the magnetic flux density
(B)
assuming a frequency
(ƒ)
of
500 Hz
, with the AL-RE101 Loop Antenna connected
to a high impedance oscilloscope input. The measured amplitude
(e
i
)
is
120
μ
V,
or 41.6 dB
μ
V
.
NOTE:
The same result can be determined
using Equation (1) and the 100 kΩ antenna
conversion factor given in Figure 4.
EQUATION (1)
Magnetic
Field Strength
(in dBpT)
=
Measured
Value
(in dBμV)
Antenna
Conversion
Factor
(in dBpT/μV)
+
97.7
dBpT
=
[41.6]
dBμV
[56.1]
dBpT/μV
+
e
i(μV)
(pT)
=
10
x
[3.144]
x
ƒ
B
(
μV
)
-6
as voltage is the known quantity, the formula is rearranged to solve for flux density...
=
(pT)
x
[3.144]
x
ƒ
10
-6
e
i(μV)
B
(pT)
(pT)
x
[3.144]
x
[500]
10
-6
[120]
=
B
(pT)
=
76,336 pT
B
(pT)
=
97.7 dBpT
(20*log[pT])
B
(pT)
substituting known variables (
voltage
and
frequency
)...
converting
linear
result into
logarithmic
units...
