MIL-DTL-49295C
4.5.2 Antenna impedance. The antenna impedance shall be measured over the frequency range of the antenna
(30 to 88 MHz) by use of a vector impedance meter or similar device. The measurement shall be made with the
antenna properly erected and terminated. A dummy load shall then be designed having the same impedance
variations across its terminals as the measured antenna impedance. A drawing shall be provided with the test plan
showing the design of the dummy load which represents the resistive and reactive components of the antenna
impedance for the complete required frequency range. Alternatively, a series of dummy loads may be designed for
4.5.3 Radiation pattern. The antenna system shall be subjected to the test of 4.3 of TIA-329 with pattern
measurements recorded at 5 MHz intervals starting at 30 MHz. Patterns in elevation and azimuth of E and H planes
shall be made with the antenna oriented for vertical polarization. This test shall demonstrate compliance with 3.4.2.6
and 3.4.2.8.
4.5.4 Transmission line and dissipation transmission line. A reflectometer shall be used to test the correct
4.5.5 Matching transformer VSWR. The antenna impedance test of 4.5.2 must be completed before the matching
transfer test can be conducted. The dummy load, designed as specified in the antenna impedance test of 4.5.2 shall
be placed across the antenna wire assembly connector of the matching transformer. VSWR shall be measured at the
matching transformer coaxial connector using commercially available equipment having a load impedance of 50
ohms, and having the capability of displaying VSWR over the complete required frequency range. VSWR shall be
observed over the complete range and recorded at the frequency having the largest VSWR (see 3.4.1.2, table II).
4.5.6 Coupling loss. For convenience of test instrumentation, two matching transformers are employed in the test
with the antenna wire assembly connectors joined together by the shortest possible connections. Test results are
adjusted to account for the doubling of effects of the test. Power from a radio frequency source having a 50 ohm
output impedance shall be fed to the coaxial connector side of one matching transformer through an in-line RF
wattmeter. The coaxial connector side of the second balun shall be connected to an RF wattmeter having a 50 ohm
load impedance. The signal source shall be adjusted to supply a fixed forward power at the in-line wattmeter. Power
4.6 Bounce/loose cargo. As a pretest, the antenna system shall be subjected to the free space VSWR test of
4.5.1.1. The antenna system shall be tested in accordance with test method 514.2, procedure XI, part 2 of
MIL-STD-810. The testing, as specified in 4.5.1.1, 4.5.1.2, 3.4.1.3 and 3.5 shall be made after loose cargo testing
4.7 Drop shock. As a pretest, the antenna system shall be subjected to the free space VSWR test of 4.5.1.1. The
antenna system, with all components stowed in the bag, shall be subjected to test method 516.2, procedure II of
MIL-STD-810. After drop test, the testing specified in 4.5.1.1, 4.5.1.2, 3.3, 3.4.1.3, and 3.5 shall be made (see
4.8 Test methods:
4.8.1 Standard test conditions. Unless otherwise specified, the following standard test conditions shall prevail
during testing.
Condition
Value/tolerance
Temperature
Prevailing ambient
Altitude
Ground level
4.8.2 Test equipment. All electrical test equipment employed, except for the RF power source, shall be
commercially available items for which calibration service, referencing back to primary standards, is available. The
RF power source for matching transformer testing may be any unmodulated generator capable of adjustment to the
required power level, capable of adjustment to the designated test frequency, and having a harmonic content of less
than 10 percent. All test equipment shall be supplied by the contractor.
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