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INSTRUCTION MANUAL
AL-RE101
LOOP ANTENNA
SECTI ON 5
-
ANTENNA THEORY
1912 1 E l T o ro R d
●
Si l vera do, Ca lifo rni a 9 26 76
●
(9 49) 459 -96 00
●
co m-p o wer. com
Rev101617
EXAMPLE CALCULATION #4:
In the following example, the antenna conversion factor
(ACF)
is calculated using
Equation (5)
and
Equation (7)
. For the purposes of this example, the frequency
(ƒ)
is assumed to be
500 Hz
, and the measuring instrument termination or load
resistance
(R
L
)
is
50 ohms
:
EXAMPLE CALCULATION #5:
In this example,
Equation (7)
is solved for magnetic flux density
(B
(pT)
)
assuming a
frequency
(
ƒ)
of
500 Hz
, with the AL-RE101 Loop Antenna connected directly to a
spectrum analyzer having an input impedance
(R
L
)
of
50 ohms
, which indicates a
measured amplitude
(V
L(
μ
V)
)
of
100
μ
V
, or
40 dB
μ
V
:
[500]
x
[3.144]
(pT/μV)
10
6
1
+
( )
2
+
[4.564x10 ]
( )
2
-6
[10]
[50]
[500]
[50]
=
[763.5]
=
(pT/μV)
ACF = 20Log
(dBpT/μV)
ACF = 20Log(
[763.5]
)
(dBpT/μV)
ACF =
57.7 dBpT/μV
V
L(μV)
(pT)
B
V
L(μV)
(pT)
B
V
L(μV)
(pT)
B
( )
[500]
x
[3.144]
(pT/μV)
10
6
1
+
( )
2
+
[4.564x10 ]
( )
2
-6
[10]
[50]
[500]
[50]
=
[100]
[763.5]
=
[100]
(pT/μV)
[100] x [763.5]
=
(pT)
97.7 dBpT
(20log[pT])
=
76,350 pT
=
(pT)
B
(pT)
B
(pT)
B
(pT)
B
(pT)
B
NOTE:
For this example, the same result
can be determined using Equation (1) and
the 50Ω 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
=
[40.0]
dBμV
[57.7]
dBpT/μV
+
