Page 17 of 22
INSTRUCTION MANUAL
AH-8055
HIGH GAIN HORN ANTENNA
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
REV051517
5.2.1 Field Strength Measurements and Example Calculations
As discussed in section 4, the measured values must be corrected for
antenna factor, preamplifier gain and any losses incurred along the
measurement path.
Figure 11 –
Typical Equipment Arrangement for Receiving Applications
EXAMPLE:
Using measurement system shown in Figure 11, a signal at 2 GHz is
observed using the spectrum analyzer, and its [uncorrected] amplitude is
exactly 60 dB
μ
V. The field strength limit at this frequency is assumed to be
500
μ
V/m
(54 dB
μ
V/m).
For the system shown above, there are four (4) correction factors needed:
1)
The AH-8055 Antenna Factor
2)
The Insertion Loss Factor for the cable connecting the AH-8055 to
the preamplifier (Cable #1)
3)
The Insertion Loss Factor for the cable connecting the preamplifier
to the spectrum analyzer (Cable #2)
4)
The gain of the RF preamplifier.
We’ll assume that the insertion loss of the Cables #1 & #2 at 2 GHz is 8 dB
and 2 dB, respectively. The preamplifier gain is 40 dB; and, by referring to
the typical antenna factor tables in Section 8, we see that the Antenna
Factor for the AH-8055 at 2 GHz is 20.82 dB/m (in practice, you will use your
actual calibrated factors rather than the typical factors). So our
calculation will be as follows:
Measured amplitude @ 2 GHz,
with a 3-meter separation distance =
60 dB
μ
V
AH-8055
Antenna Factor @ 2 GHz =
20.82 dB/m
Insertion Loss of Cable #1 @ 2 GHz =
8 dB
Insertion Loss of Cable #2 @ 2 GHz =
2 dB
Preamplifier Gain @ 2 GHz =
40 dB
=
50.82 dB
μ
V/m
FCC Part 15 Field Strength Limit @ 3 meters =
54 dB
μ
V/m
Limit
Δ
(margin) =
-3.18 dB
Antenna Factor (dB/m)
+
Measured Value (dBμV)
Field Strength (dBμV/m)
=
Preamp Gain Factor (dB)
-
Insertion Loss Factors (dB)
+
RF
PREAMPLIFIER
