ETS-Lindgren 3142C Biconilog Antenna (Archived) - Manual (Page 17)

5.0 Application
5.1 Without Optional End Plates
For emissions measurements, electric fields strength in dB[V/m] is obtained from:
E(dB[V/m]) = V(dB[V]+AF(dB[1/m])+
α
(dB)
V = the receiver or spectrum analyzer voltage reading
AF = antenna factor
α = cable loss, if cable losses are non-negligible
For immunity testing, the electrical 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
An estimate of the power required for any field strength E can be obtained from
Model 3142C Typical 1 V/m Power Required
on page Error! Bookmark not
defined.Error! Bookmark not defined.Error! Bookmark not defined. , which
shows power required in watts to generate 1 V/m. Power shown is calculated
from the measured gain and corrected for VSWR. For any other field strength,
multiply the power in watts by desired E-field squared, or:
P(E V/m) = E 2
P(1 V/m)
n estimate of the power required, taking
VSWR into account, is obtained from:
P f = P n / {1-[(VSWR-1)/(VSWR+1)]
2
}
Actual transmitted field strength should be verified using an ETS-Lindgren
electric field probe, or an equivalent. A
P f
= forward (amplifier output) power
P n
= new power as discussed
Application | 17
Archived 01/19/11