MIL-PRF-55359A(CR)
The measurement in this test shall not change more than five (5%) percent from the value
measured prior to subjection to the test condition; in no event shall the measurement exceed the
specified limit. VSWR shall be measured during the temperature and humidity tests while the
antenna is in chamber, in addition to tests prior and subsequent to those environmental tests. Any
type of chamber or adequate size to hold the specified ground plane will suffice for these tests
since only a possible change in the VSWR is looked for. A pre-test VSWR is to be made to
obtain a chamber reference VSWR.
4.6.1 Temperature-altitude test. The temperature altitude test of the Appendix shall be
performed. The antenna shall be non-operating during application of environmental conditions
other than normal room ambient.
4.6.2 Humidity test. The following humidity test shall be performed. Subject a sample to
natural cyclic high humidity conditions under randomly varied temperatures between 79°F and
95°C with relative humidity randomly varied between 79 and 100% over a 24 hour period.
Stabilize the test item at ambient conditions for another 24 hours. A VSWR test in accordance
with 4.5.2 shall be performed as soon as practicable after the completion of the test, but not later
than 1/2 hour after completion (see 3.10.2).
4.6.3 Vibration test (see 3.11.3). The following vibration test shall be performed.
MIL-STD-810, Method 514.1 may be used as a guide, but its use is not mandatory.
4.6.3.1 Procedure. Vibration amplitudes and frequencies shall be measured by techniques
that will not significantly affect test item control or response. The input control sending device(s)
shall be rigidly attached to the vibration table at, or as near as possible to the attachment point(s)
of the test item.
a. Measure the VSWR in accordance with 4.5.2. Record the data.
b. The vibration shall be applied along each of the three mutually perpendicular axes of
the test item. The vibratory acceleration levels or double amplitudes of the test curve in figure 4
shall be maintained at the test item mounting points.
c. Resonant frequencies of the test item shall be determined by varying the frequency of
applied vibration slowly through the specified range at reduced test levels but with sufficient
amplitude to excite the item. Sinusoidal resonance search may be performed using the test levels
of figure 4. If the test levels of figure 4 are used, the time spent for this test can be counted as
part of the total required test time.
d. The test item shall be vibrated along each axis at the most severe resonant frequencies
determined in step c. Test levels and frequency ranges shall be in accordance with figure 4. If
more than four significant resonant frequencies are found for any one dwell time at each
resonance shall be 30 minutes. If a change in the resonant frequency occurs during the test, its
time of occurrence shall be recorded, and immediately the frequency shall be adjusted to maintain
the peak resonance condition. The final resonant frequency shall be recorded.
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