ETS-Lindgren 3142D BiConiLog Antenna (Archived) - Manual (Page 36)

36 | Application
An estimate of the power required, taking VSWR into account, is obtained from:
P
f
= P
n
/ {1-[(VSWR-1)/(VSWR+1)] 2 }
P f = forward (amplifier output) power
P n = new power, as discussed
For IEC/EN 31000-4-3 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 uniform field specifications.
It is usually necessary to place RF absorbing material between the EUT and
antenna to suppress ground plane reflection to ensure the field uniformly, or to
conduct the immunity test in a fully-lined anechoic room. In general, closer
distances require less power to create a given field strength.
With Optional End Plates
For emissions testing it is recommended that the Model 3142D BiConiLog™
Antenna 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 immunity testing, the electric field strength generated at a distance d can be
approximated by:
 
E
Pg
d
V / m

30
d = distance, in meters
g = numeric gain (10
G[dB]/10
)
P = antenna net input power, in watts
Actual transmitted field strength should be verified using an ETS-Lindgren
electric field probe, or equivalent.
Archived 6/19/13