equipment used shall have been calibrated within the last 12 months.
3.7.5.1
Test Procedure
Test procedure and equipment shall be similar to that specified in
MIL-STD-188-125-1. Test frequencies are specified herein. Test points
shall be as indicated in Table I. Corner points of the grid shall occur at
the intersection of three planes (two-wall surfaces and ceiling or two wall
surfaces and floor). Measurement data at all test points shall be
recorded, and a grid map for each surface tested shall be provided. For
any test point where required attenuation is not provided, the Contractor
shall correct the discrepancy and retest. Both the results of the test
failure and the successful results shall be provided. Enclosure
effectiveness test for magnetic attenuation shall be performed with the
antennas located directly opposite each other and separated by a distance
of 600 mm 2 ft plus the wall thickness. Plane wave attenuation tests shall
be performed with the antennas located directly opposite each other and
with the transmitting antenna placed 300 mm 1 ft away from the enclosure
wall and with the receiving antenna set 300 mm 1 ft from the wall for
stationary measurements and 50 to 600 mm 2 inch to 2 ft from the wall for
swept measurements. The magnetic field test and the plane wave test shall
be performed using the following sequence. The calibrations shall be
performed at the beginning of each test day. Then the test area shall be
set up for the 100 to 400 MHz stationary measurement in on to the two
required polarizations. With the transmitter off check the receiver
sensitivity. Energize the transmitter, and record the fixed measurement
data. Remove the receiving antenna from the test stand and perform the
swept measurement at the same frequency and transmitting antenna
polarization. Rotate the transmitting antenna, and perform the second 100
to 400 MHz stationary measurement. Perform the swept measurement for the
second transmitting antenna polarization. Reconfigure the equipment for
the 900 to 1000 MHz test frequency, and repeat the series of four
measurements. To perform the swept measurement, remove the receiving
antenna from the test stand and hold with a dielectric rod at least 300 mm
12 in in length. A dielectric spacer shall be attached to the sweeping
antenna to assist in maintaining the 50 mm 2 in distance from the shield.
A rapid sweep to locate hot spots shall be made by rotating the
polarization and waving the antenna through the specified volume. The
final activity of each test day shall be to repeat the calibrations and
verify the consistency with the previous calibration results. Test
procedures shall include a definition of all test points including but not
limited to walls, door frames, accessible joints, and around filters and
penetrations. Each EM door shall be tested at the locations indicated in
Table I.
TABLE I - SHIELDING EFFECTIVENESS TEST POINTS
Testing Location
Test Points Spacing
Joints between steel panels for
Test every 3 m (Note 1)
roof, walls, and floors
(minimum of one test point per
side)
Corner seams for walls
Test every 3 m (Note 1)
to floor, walls to roof,
(minimum of one test point per
and wall to wall
corner seam)
Corners (intersection of
Test at all corners in shield
three surfaces)
SECTION 13095A
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