ETS-Lindgren 3142C Biconilog Antenna (Archived) - Manual (Page 18)

For IEC 1000-4-3 type testing, the antenna tip can be placed at any distance
between one and three meters from the EUT as long as the front face plane is
illuminated according to the –0,+6 dB specification.
5.2 With Optional End Plates
For emissions testing it is recommended that the Model 3142C be used without
the optional end plates. The coupling of the endplates to ground will create
higher uncertainty values, particularly in the vertical polarization.
For more information about this issue, see “Understanding the
Measurement Uncertainties of the Bicon/log Hybrid Antennas” by
Zhong Chen in the 1999 issue of the International Journal of EMC.
For immunity testing, the electric field strength generated at a distance d can be
approximated by the formula:
( )
E
Pg
d
V / m
=
30
d = distance, in meters
g = numeric gain (10 G[dB]/10 )
P = antenna net input power, in watts
An estimate of the power required for any field strength E can be obtained from
Model 3142C Typical 26-3000 MHz 1M Forward Power
on page 23 or Model
3142C Typical 26-3000 MHz 3M Forward Power on page 24, which shows power
required in watts to generate 1 V/m. For any other field strength not shown,
multiply the power in watts by the desired E-field squared, or
( ) ( )
P E E P V / m V / m
= 2
1
Actual transmitted field strength should be verified using an ETS-Lindgren
electric field probe, or an equivalent. For IEC 1000-4-3 type testing, the antenna
tip can be placed at any distance between one and three meters from the EUT as
long as the front face plane is illuminated according to the –0,+6 dB specification.
In general, closer distances require less power to create a given field strength.
18 | Application
Archived 01/19/11