ETS-Lindgren 5411 GTEM! Test Cell - Manual (Page 41)

GTEM! Use
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The EUT array, a personal computer system installed on a plywood panel per the
requirements of ANSI 63.4-1992, is shown with the x, y, z EUT axes aligned with
the X, Y, Z GTEM! axes. Note that the EUT and GTEM! axes are shown in
alignment at the top, right sides, and bottom of Typical EUT System Installed in
Large GTEM! on page 43. The circle with the dot at the center located at the
bottom of the illustration represents the tip of the axis arrowhead pointing out.
In position two, the EUT is rotated so that the y-axis aligns with the X-axis, the
z-axis aligns with the Y-axis, and the x-axis aligns with the Z-axis. Typical EUT
System Installed in Large GTEM! (90
° Rotation) on page 44 demonstrates the
alignment of the GTEM! and EUT axes for this rotational position.
In position three, the EUT is rotated so that the x-axis aligns with the X-axis, the
x-axis aligns with the Y-axis, and the y-axis aligns with the Z-axis. Typical EUT
System Installed in Large GTEM! (Additional 90
° Rotation) on page 45 shows the
third position.
Measurement Procedure
The following general procedure should be used to perform radiated emissions
measurements in a GTEM!. This procedure is written for manually-performed
measurements.
1. Install the EUT in the center of the test volume of the GTEM! with a
reference orientation, as shown in Typical EUT System Installed in Large
GTEM! on page 43 and as described previously for the first position.
2. Measure the RF voltages emanating from the EUT as a function of
frequency over the desired frequency range. Depending on the
measurement device used, either peak, quasi peak, or average
measurements may be made. These measurements are collectively
referred to as V
xyz
versus frequency.
3. Rotate the EUT through two successive 90-degree rotations to the right,
such that the x-axis is replaced by the y-axis, and so on, as shown in
Typical EUT System Installed in Large GTEM! (90
° Rotation) on
page 44.
4. Measure the RF voltages emanating from the EUT as a function of
frequency over the desired frequency range. These measurements are
referred to as V
yzx
versus frequency.