ETS-Lindgren 5411 GTEM! Test Cell - Manual (Page 88)

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Radiated Emissions Test Performance of GTEM!
Conclusions
The following conclusions are drawn after conducting the testing described and
after review and analysis of the test results.
T
EST
P
ROCEDURE
S
PECIFIC
C
ONCLUSIONS
 Must Control EUT Configuration—There are several issues connected with
this statement. An early procedure tried for the three orthogonal rotations
was to rotate each component in place. This was quickly discarded in favor
maintaining right relative positions of the components in EUT like a personal
computer system.
 Must Manage Cable Placement—The relative positions of the
interconnecting and power cables should be managed to maintain the EUT
configuration to provide the highest levels of emanations from the EUT array.
 Must Manage EUT Performance by Operating Software—The
GTEM! may be scanned in frequency at rates much higher than are normally
associated with commercial EMC testing. The exercising software must be
written with this in mind. For example, the optimal software approach in a
GTEM! test is to write a single
H to the screen and the printer, not a string
of 80.
 Must Use Precision Methods for Conduct of Measurements—The care
that is normally taken by conscientious test personnel is adequate. For
GTEM! to OATS testing it was found that it is necessary to characterize
measurement accessories such as preamplifiers and coaxial cables to a
precision of 0.1 dB to achieve meaningful results.
M
ORE
G
ENERAL
C
ONCLUSIONS
 Direct comparison of dipole and personal computer measurements indicates
a successful comparison measurement program.
 Statistical analysis indicates the direct comparison of GTEM! data and
OATS data from a variety of devices and conditions is statistically valid.
 The GTEM! is a viable alternative facility for conducting radiated emissions
testing.
 The time savings in the testing can be more than 8:1 in favor of the GTEM!.
This indicates that higher test efficiency will allow substantially more testing
to be done in the same amount of time as long as this is possible in a
practical sense.