ETS-Lindgren 3147 Log Periodic Dipole Array Antenna - Manual (Page 31)

7.0 Radiated Emissions Measurement
Before connecting any components, follow the
safety information in the ETS-Lindgren
Product Information Bulletin included with your
shipment.
Ambient field strength values are measured as follows:
1. Install the antenna where measured field strength values are desired.
2. Select the desired orientation of the antenna, both boresite direction
and polarization.
3. Connect the antenna output connector to the input of the receiving
system using a coaxial cable. These antennas are calibrated for
receiving systems having 50-Ω input impedance. Other values of
receiving system input impedance will require correction for the
differences in input impedance.
4. Select the desired frequency of measurement on the receiving system.
5. Measure the RF voltage, Va, referenced to the input port of the
receiving system. The units of the measurement should be in dB
referenced to 1 microvolt, dB(µV). If the units of measurement as
displayed by the receiver are not dB(µV), for example, in millivolts, they
should be converted to microvolts and then converted to dB(µV) by:
Va = 20 x log 10 (RF voltage in microvolts)
Va = 20 x log 10 v d
6. To determine the field strength at the frequency of the observation, add
the voltage reading from the receiving system in dB(µV) to the value
given by the antenna factor chart at that frequency in dB (m
-1
):
RF Voltage, dB(µV) + Antenna Factor dB (m
-1
) =
Field Strength dB (µV/m)
Ea = Va + AF
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