1、AMSC N/A FSC 5985 MIL-DTL-49295C 20 June 2013 SUPERSEDING MIL-DTL-49295B 16 October 2006 DETAIL SPECIFICATION ANTENNA GROUP OE-303( )/GRC This specification is approved for use by all Departments and Agencies of the Department of Defense. 1. SCOPE 1.1 Scope. This specification covers a broadband dir
2、ectional VHF antenna system to be designated as Antenna Group OE-303( )/GRC. The OE-303 is also referenced herein as: The antenna system. 2. APPLICABLE DOCUMENTS 2.1 General. The documents listed in this section are specified in sections 3 and 4 of this specification. This section does not include d
3、ocuments cited in other sections of this specification or recommended for additional information or as examples. While every effort has been made to ensure the completeness of this list, document users are cautioned that they must meet all specified requirements of documents cited in sections 3 and
4、4 of this specification, whether or not they are listed. 2.2 Government documents. 2.2.1 Specifications, standards, and handbooks. The following specifications, standards, and handbooks form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these docum
5、ents are those, cited in the solicitation or contract (see 6.2). DEPARTMENT OF DEFENSE SPECIFICATIONS MIL-DTL-14072 - Finishes for Ground Based Electronic Equipment. DEPARTMENT OF DEFENSE STANDARDS MIL-STD-202 - Electronic and Electrical Component Parts. MIL-STD-252 - Classification of Visual and Me
6、chanical Defects for Equipment, Electronic, Wired, and Other Devices. MIL-STD-810 - Environmental Engineering Considerations however, final acceptance and shipment will be withheld until group C re-inspection results have shown that the corrective action was effective. 4.4.3 3 Re-inspection of confo
7、rming group C sample units. Unless otherwise specified, sample units which have been subjected to and passed group C inspection may be accepted on the contract or order provided all damage is repaired and the sample units are resubjected to and pass groups A and B inspection. 4.5 Electrical performa
8、nce. 4.5.1 Antenna array. The contractor shall perform the following tests on the antenna system to demonstrate performance in accordance with the specification requirements. 4.5.1.1 Free space VSWR. The test shall be in accordance with TIA-329 except that the measurement shall be performed with a v
9、ector impedance meter or other instrument of equivalent accuracy (see 3.4.2.4). 4.5.1.2 RF power capability. The antenna system shall be installed using a metal mast. To electrically include the mast insulator in the test, a ground connection shall be completed between the support mast section and t
10、he ground side of the input matching transformer ground connector. Three hundred and fifty (350) watts of power shall be applied to the assembly at the input matching transformer connector. The power source shall be a continuous wave, radio frequency source having a nominal output impedance of 50 oh
11、ms. The test frequency shall be at a high end of the specified frequency range. Power shall be applied for a period of 30 minutes. During the period when power is applied, the insulation material shall be observed for evidence of RF flashover or leakage. After power is removed the insulation materia
12、l shall be inspected for evidence of RF flashover or leakage. Evidence of RF flashover or leakage shall constitute a failure. The test shall be completed within 1 hour of the time of completion of exposure to the environmental condition (see 3.4.2.7 and 4.10). 4.5.1.3 Matching transformer power. For
13、 convenience of test instrumentation, two matching transformers are employed in the test with the balanced sides joined together by the shortest possible connections. Both matching transformers are subjected to the service conditions and the results are adjusted to account for the doubling to effect
14、s of the test. Power from a radio frequency source having a 50 ohm output impedance shall be fed to the coax connector of one matching transformer through an in-line RF wattmeter capable of measuring forward and reverse power. The coax connector of the second balun shall be connected to an RF wattme
15、ter having a 50 ohm load impedance. The signal source shall be adjusted to supply 200 watts forward power at the in-line wattmeter. VSWR shall be measured at the in-line wattmeter and coupling efficiency shall be observed by measuring power at the load wattmeter (see 3.4.1, table II). 4.5.1.4 Dielec
16、tric withstanding voltage. The antenna system shall be subjected to the test in accordance with method 301 of MIL-STD-202 (see 3.4.2.9). 4.5.1.5 Antenna gain test. The relative power gain of the antenna compared to a half-wave dipole, adjusted to resonance, shall be measured. The gain of the array a
17、nd dipole shall be recorded and compared at 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, and 88 MHz. The gain shall meet the requirements of 3.4.2.5 with the test conducted in vertical polarization. The requirements of 3.4.2.6 and 3.4.2.8 shall also be satisfied (see 3.4.2.5, table III). Provided
18、 by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-49295C 10 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 sh
19、all 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 resi
20、stive and reactive components of the antenna impedance for the complete required frequency range. Alternatively, a series of dummy loads may be designed for the same purpose and drawings for each shall be attached to the test plan (see 3.4.2.3, table II). 4.5.3 Radiation pattern. The antenna system
21、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.
22、4.2.8. 4.5.4 Transmission line and dissipation transmission line. A reflectometer shall be used to test the correct impedance and continuity (see 3.4.2.3, table II). 4.5.5 Matching transformer VSWR. The antenna impedance test of 4.5.2 must be completed before the matching transfer test can be conduc
23、ted. 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 impedanc
24、e 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 match
25、ing 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
26、 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.
27、Power at the load wattmeter shall be measured and loss computed (see 3.4.1.1, table II). 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 o
28、f 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 (see 3.5.8, table IV). 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 t
29、he 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 3.5.10, table IV). 4.8 Test methods: 4.8.1 Standard test conditions. Unless otherwise specified, the following standard t
30、est 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 b
31、ack 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 equ
32、ipment shall be supplied by the contractor. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-49295C 11 4.8.3 Reference dipole antenna. The reference dipole antenna for gain measurements shall be a vertically polarized balanced dipole. Length o
33、f the dipole shall be continuously adjustable. At each test frequency, length shall be adjusted to half-wave length resonance, considering end effects (usually 95 percent to 97 percent of one half wave length). When so adjusted, free space VSWR shall be less than 2.0 to 1. The coupling balun shall h
34、ave a 1 to 1 impedance ratio. Balun coupling loss shall be less than 1 dB. The transmission line shall be the same line or an identical line to that of the antenna under test. Free space VSWR of the antenna and coupling loss of the balun shall be measured over the frequency range of the antenna unde
35、r test. Maximum VSWR and maximum coupling loss shall be recorded in the space provided for on the test data sheet for gain measurements. A typical antenna for this purpose is shown in figure 1. NOTES: 1. Indiana General part # F624-19, 02, ferramic toroid or equal with 10 turns #18 enameled wire, tr
36、ifilar winding. 2. Whip sections must extend anywhere from 25 feet to 8.5 feet to adjust to frequency of measurement. 3. Value of capacitor to be selected so as VSWR of the balun is 1:1 across the frequency range of the balun. FIGURE 1. Reference dipole antenna. Provided by IHSNot for ResaleNo repro
37、duction or networking permitted without license from IHS-,-,-MIL-DTL-49295C 12 4.9 Mechanical tests. 4.9.1 Performance of test. Every joint, screw, seam, gasket, and any other area where two pieces interface on the balun housing subassembly half of the matching transformer shall be thoroughly painte
38、d with a soap and water solution. Without touching the painted half, carefully place the matching transformer into the vacuum chamber in a manner that will allow close visual examination of the painted portion while the vacuum chamber is being operated. While the balun housing subassembly is still w
39、et from the painted soap and water solution, a vacuum of 2.5 psig shall be applied to the chamber interior. While the vacuum is being maintained, there shall be no leaks, as evidenced by bubbling or sputtering of the wet solution. If there is a leak(s), rework shall be accomplished. Detection of a l
40、eak(s) at this stage shall be considered as having failed this test. The reworked area(s) shall then be re-inspected in accordance with standard industry practice. 4.9.2 Housing plate assembly. The matching transformer shall be placed in a position that allows access to all exterior joints and faste
41、ners on the housing plate assembly surface and shall be tested as follows. 4.9.2.1 Performance of test. Every joint, screw, seam, gasket, and any other area where two pieces interface on the housing plate assembly half of the matching transformer shall be thoroughly painted with a soap and water sol
42、ution. Without touching the painted half, carefully place the matching transformer into the vacuum chamber in a manner that will allow close visual examination of the painted portion while the vacuum chamber is being operated. While the housing plate assembly is still wet from the painted soap and w
43、ater solution, a vacuum of 2.5 psig shall be applied to the chamber interior. While the vacuum is being maintained, there shall be no leaks, as evidenced by bubbling or sputtering of the wet solution. If there is a leak(s), rework shall be accomplished. Detection of a leak(s) at this stage shall be
44、considered as having failed this test. The reworked area(s) shall then be reinspected in accordance with 4.9.2. 4.10 Environmental tests. The antenna system shall be subjected to the environmental tests specified below. Prior to each test, the test items shall be subjected to the free space VSWR tes
45、t (see 4.5.1.1) and shall meet the requirements of 3.4.2.4. Immediately after exposure to each environmental test specified below the test items shall be subjected to the following inspections: RF power level of 4.5.1.2; dielectric withstanding voltage of 3.4.2.9; free space VSWR of 4.5.1.1; and ser
46、vice conditions of 3.5. Specific tests may be waived, with Government approval, for those items which have previously been qualified. 4.10.1 Temperature. The antenna shall be subjected to the following temperature tests. 4.10.1.1 High temperature. The antenna system shall be subjected to the test of
47、 method 501.5, procedure II of MIL-STD-810. At steps 4 and 7, the chamber temperature shall be 71C (+160F). During step 8, the matching transformers shall be subjected to the matching transformer power test, 4.5.1.3, for one hour. During the test all items of the antenna system shall be stowed in th
48、e bag except for the matching transformer. After exposure, the tests of 4.5 shall be conducted. When any combination of high temperature, low temperature and immersion are done on the same sample, 4.5.3 need only be done once after completion of these tests (see 3.5.1a, table IV). 4.10.1.2 Low tempe
49、rature. The antenna system shall be subjected to the test of method 502.5, procedure I of MIL-STD-810. During step 2, the chamber temperature shall be maintained at -57C (-70F) for not less than 2 hours after stabilization of the test items. Delete step 3. During step 4, the chamber temperature shall be maintained at -45.6C (-50F) for not less than 4 hours after stabilization of the test items. During step 5, the matching transformers shall be subjected to th
