Specifications

EMC-CS-2009.1
© Copyright Ford Motor Company – All Rights Reserved Page 96 of 121
February 11, 2010
The chamber meets the field uniformity requirements if the standard deviation from the individual axes (x, y, and z), and
the total data set (all axes) are less than 3 dB (a maximum of three frequencies per octave may exceed the allowed standard
deviation by no greater than 1 dB).
C1.1.2 Receive Antenna Calibration
The receive Antenna Calibration Factor (ACF) for an empty chamber is established to provide a comparison with a loaded
chamber. The ACF for each frequency is:
s
f10for3,
s
f10for8
Input
cReAve
P
P
ACF
≥≤
=
Where:
P
Input
is the average input power from C1.1.1 g) for the location at which the average received power P
AveRec
from C1.1.1
g) was measured
C1.1.3 Chamber Insertion Loss
The chamber Insertion Loss (IL) for the chamber is given by the following:
s
f10for3,
s
f10for8
Input
cReMax
P
P
IL
≥≤
=
Where:
P
Input
is the average input power from C1.1.1 g) for the location at which the maximum received power P
MaxRec
from
C1.1.1 g) was measured.
C1.1.4 Maximum Chamber Loading Verification
The following procedure is used to determine if the chamber is affected by a DUT which loads (absorbs a significant
amount of energy) the chamber. This procedure should be performed once in the life of the chamber or whenever the
chamber has undergone major structural modifications. Prior to each test, a chamber calibration shall be performed
according to C2.
a) Install a significant amount of absorbing material (e.g., foam absorber) in the chamber to load the chamber to the
amount expected during normal testing (a factor of sixteen or 12 dB is typical).
b)
Repeat the calibration procedure from C1.1 using eight or three locations of the field probes according to the
frequency (eight < 10 fs, three > 10 fs). The electric field probes and receive antenna should be a minimum of 0.25 m
away from any absorbing material. Determine the chamber loading by comparing the ACF of an unloaded chamber
with the ACF of a loading chamber as follows:
ChamberLoaded
ChamberEmpty
ACF
ACF
Loading =
c)
Repeat the field uniformity calculations as described in C1.1.1.
d)
If either the field uniformity of the individual rectangular components or the field uniformity for all axes (x, y, and z)
is greater than the allowed standard deviation indicated in C1.1.1 d), then the chamber has been loaded to the point
where field uniformity is unacceptable. Reduce the amount of loading and repeat the loading effects evaluation.