1、Designation: E1851 09E1851 15Standard Test Method forElectromagnetic Shielding Effectiveness of Durable RigidWall Relocatable Structures1This standard is issued under the fixed designation E1851; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This te
3、st method covers the determination of the electromagnetic shielding effectiveness of durable relocatable shieldedenclosures.1.1.1 The intended application of this test method is for virgin shielded enclosures that do not have any equipment or equipmentracks. It is recommended that tests be conducted
4、 before the interior finish work begins. However, the shield assembly includingall enclosure penetrations shall be completed and required penetration protection devices shall be installed in accordance with thedesign specification. The test method can also be used on existing shielded enclosures aft
5、er repair work is done to verifyworkmanship, but it may be necessary to remove equipment or equipment racks to gain access to a test area.1.1.2 The test procedures delineated in this document are comprehensive and may require several days to complete for aroom-size shielded enclosure. A user can app
6、ly this test method for a first article test that requires proof of concept and validationof design and fabrication technique. Appendix X2 provides guidance on choosing test points so shielding effectiveness tests on aroom-size shielded enclosure may be completed in about one-half day for which it a
7、pplies to shielded enclosures coming off anassembly line.1.2 This test method is for use in the following frequency ranges: 140 to 160 kHz, 14 to 16 MHz, 300 to 500 MHz, 900 to 1000MHz, and 8.5 to 10.5 GHz. Specific test frequencies within these ranges are required (see 10.1.111.1.1 and 11.2.110.2.1
8、).).Additional measurements in the range of 10 kHz to 10.1.5.110.5 GHz may be performed. For specific applications, the frequencyrange may be extended from 50 Hz to 40 GHz. Appendix X1 provides guidance on selecting measurement frequencies.1.3 This test method is not applicable to individual compone
9、nts such as separate walls, floors, ceilings, or shielded racks.1.4 This standard may involve hazardous materials, operations, equipment, or any combination.1.5 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only.1.6 This standard does
10、 not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standar
11、ds:2E631 Terminology of Building ConstructionsE1749 Terminology Relating to Rigid Wall Relocatable Shelters2.2 IEEE Standards:3IEEE Std 299-1997 IEEE Standard Method for Measuring the Effectiveness of Electromagnetic Shielding EnclosuresIEEE Std C95.1-1991 IEEE Standard for Safety Levels with Respec
12、t to Human Exposure to Radio Frequency ElectromagneticFields, 3 kHz to 300 GHz1 This test method is under the jurisdiction of ASTM Committee E06 on Performance of Buildings and is the direct responsibility of Subcommittee E06.53 on Materialsand Processes for Durable Rigidwall Relocatable Structures.
13、Current edition approved Nov. 1, 2009Sept. 1, 2015. Published December 2009September 2015. Originally approved in 1997. Last previous edition approved in 20042009as E1851 04.E1851-09. DOI: 10.1520/E1851-09.10.1520/E1851-15.2 For referencedASTM standards, visit theASTM website, www.astm.org, or conta
14、ctASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from Institute of Electrical and Electronics Engineers, Inc. (IEEE), 445 Hoes Ln., P.O. Box 1331, Piscataway, NJ 08854-1331,08
15、854-4141, http:/www.ieee.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends
16、 that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12.3 Military Standa
17、rd:4MIL-STD-188-125 High Altitude Electromagnetic Pulse (HEMP) Protection for Ground Based C4I Facilities PerformingCritical, Time-Urgent Missions2.4 OSHA Standard:5OSHA Regulation, 29 CFR 1910, Department of Labor, July 19924 Available from Standardization Documents Order Desk, DODSSP, Bldg. 4, Sec
18、tion D, DLA Document Services, Building 4/D, 700 Robbins Ave., Philadelphia, PA19111-5098, http:/dodssp.daps.dla.mil.19111-5094, http:/quicksearch.dla.mil.5 Available from Occupational Safety and Health Administration (OSHA), 200 Constitution Ave., NW, Washington, DC 20210, http:/www.osha.gov.E1851
19、1523. Terminology3.1 DefinitionsSee Terminologies E631 and E1749 for definitions of general terms used in this test method.4. Summary of Test Method4.1 Test ConfigurationA transmitting antenna is connected to an electromagnetic source set to a specific frequency andamplitude.Areceiving antenna is pl
20、aced a specified distance from the transmitting antenna, and the received electromagnetic fieldlevel is recorded as a reference or calibration measurement.The transmitting antenna and electromagnetic source are placed outsidethe shielded enclosure. The receiving antenna and associated test equipment
21、 are placed inside the shielded enclosure. Thetransmitting and receiving antennas separation, frequency, and amplitude are the reference measurements. The transmitting andreceiving antennas are at the same height for a given test point. The received electromagnetic field level is recorded as the tes
22、tmeasurement. The ratio of the test measurement to the reference measurement is the electromagnetic shielding effectiveness of theshielded structure at the measurement location and frequency. The logarithm of this ratio is typically used in expressing theshielding effectiveness in decibels.4.2 Test
23、FrequenciesA summary of nominal test frequencies and corresponding test configurations is shown in Table 1.5. Significance and Use5.1 This standard provides measurement procedures for determining the electromagnetic shielding effectiveness of durable rigidwall relocatable shielded enclosures. This s
24、tandard specifies a method for comparing the shielded enclosure performance ofstructures provided by different suppliers. In addition, this standard is written to minimize variations in measured shieldingeffectiveness at a given frequency and test point regardless of test personnel, equipment, and t
25、est site. Therefore, the shieldingeffectiveness of a durable rigid wall relocatable shielded enclosure of any size from any supplier can be determined. This standardspecifies a minimum set of measurements at a given frequency and a minimum set of frequencies to determine shieldingeffectiveness.5.2 S
26、ource FieldsPerformance of a shielded enclosure is to be assessed for two source fields: magnetic and plane wave.5.2.1 Magnetic Field MeasurementsThe attenuation provided by a shielded enclosure is assessed by using a local source togenerate the near field. The magnetic field measurements are specif
27、ied for two narrow frequency bands: 140 to 160 kHz and 14to 16 MHz.5.2.2 Plane Wave MeasurementsThe attenuation provided by a shielded enclosure is assessed by using a locally generateddistant source or plane wave field. The plane wave measurements are specified for three narrow frequency bands: 300
28、 to 500 MHz,900 to 1000 MHz, and 8.5 to 10.5 GHz.6. Interferences6.1 Interference with Electronic EquipmentCare shall be taken to avoid interference with other electronic equipment operatingin the vicinity.6.2 Operational Impact Analysis and RiskThe electromagnetic barrier must remain intact during
29、the shielding effectivenessmeasurement sequence, and use of electrically noisy equipment must be restricted. Therefore, construction activity or unusualoperations (facility modification or maintenance) may be affected. Radiated signal levels should present no hazard to equipment,but frequency adjust
30、ments may be required to avoid self interference or interference with nearby facilities. Record the actual testfrequencies. Normal electrical safety precautions apply.7. Apparatus7.1 The required apparatus is identified in Table 2. Choose test equipment that provides a dynamic range of at least 10 d
31、B (20dB is preferable (see Note 1) in excess of the shielding effectiveness requirement at the test frequency.TABLE 1 Test Frequencies and Test ConfigurationsNominal Test Frequency Corresponding TestConfiguration150 kHz and 14 MHz Fig. 1400 MHz, 1000 MHz, and 10 GHz Fig. 2E1851 153NOTE 120 dB of dyn
32、amic range makes the test easier to perform by less experienced personnel. The standard uses a minimum of 10 dB becauseit offers a lower cost solution to testing durable rigid wall relocatable structures. If the existing test equipment has 20 dB of dynamic range then 20 dBof dynamic range should be
33、used. It makes the hot spots stand out more clearly from the background noise on the LCD displays on spectrum analyzers.8. Hazards8.1 For human exposure to electromagnetic energy in controlled environments, the maximum permissible exposure to electricand magnetic field strengths shall be minimized t
34、o the maximum extent possible. Acceptable levels can be found in IEEEStd C95.1-1991 and OSHA Regulation, 29, CFR.9. Preparation of Apparatus9.1 New and Existing Durable Relocatable Enclosure TestingTesting of new durable rigid wall relocatable shielded enclosurescan be conducted at the manufacturing
35、 site. Manufacturing site testing can locate structural defects or weaknesses or both andcorrections may be easily implemented. For existing structures, weaknesses can be determined and corrected during maintenanceor periodic retesting.9.2 Movable EquipmentMoveable equipment containing metal, not no
36、rmally housed in the enclosure or attached outside theenclosure, shall be removed from the enclosure prior to making measurements.9.3 Preliminary ProceduresPerform the following preliminary test on all accessible shielding faces to detect weak points andto permit remedy of shielding defects caused b
37、y faulty assembly and poor workmanship prior to actual measurement.9.3.1 With the transmitting antenna turned off, perform a continuous wave (cw) measurement at each frequency to be used fortesting to ensure that no emitters are nearby that may cause interference. Frequency adjustments may be necess
38、ary to avoidinterference. Setup for this measurement is the reference measurement (see Section 910 and Fig. 1a and Fig. 2a).9.3.2 Additionally, perform a receiving equipment coupling measurement. The setup for this measurement is the referencemeasurement (Section 910) with the following exceptions.
39、Disconnect the receiving antenna from the nearest cable and replacethe receiving antenna with a dummy load (resistive load matched to the characteristic impedance of the receiving system) as shownin Fig. 3. Measured levels shall be negligible so the required dynamic ranges are maintained. If the mea
40、sured levels are larger thanTABLE 2 Test ApparatusEquipment CharacteristicsOscillator(s) 140 to 160 kHz, 14 to 16 MHz, 300 to 500 MHz,900 to 1000 MHz, 8.5 to 10.5 GHzPower Amplifier(s) 140 to 160 kHz, 14 to 16 MHz, 300 to 500MHz,A 900 to 1000 MHz,A 8.5 to 10.5 GHz,amplification and noise figures as
41、required fordynamic rangePreamplifier(s) 140 to 160 kHz, 14 to 16 MHz, 300 to 500 MHz,900 to 1000 MHz, 8.5 to 10.5 GHz,amplification and noise figures as required fordynamic rangeReceiver(s)/SpectrumAnalyzer(s)140 to 160 kHz, 14 to 16 MHz, 300 to 500 MHz,900 to 1000 MHz, 8.5 to 10.5 GHzAntenna Kit 1
42、40 to 160 kHz,B 14 to 16 MHz,B 300 to 500MHz,C 900 to 1000 MHz,C 8.5 to 10.5 GHzDMiscellaneous Cables andAttenuators as RequiredEA The power amplifier output is usually matched to an unbalanced to balanced(balun) transformer; the balanced output is matched to a balanced dipole.B Circular loop antenn
43、a whose diameter is 30 cm (1 ft) shall be used. The shieldedcircular receiving antenna can have multiple turns, but the total length of wireforming the loop shall be less than 16 wavelength.C Any antenna that radiates at the prescribed frequencies may be used. However,antennas that require a large c
44、lear space in the direction of wave propagation shallnot be used where clear space is limited for testing. Examples of such antennasare linearly polarized log periodic dipole and circularly polarized conical spiralantennas. Procedures are written assuming use of dipole antennas for plane wavemeasure
45、ments. If a dipole antenna is used as a receiving antenna, its length shallbe less than 16 of wavelength. The receiving antenna is usually connected to abalun then to an attenuator.D Any antenna that radiates at the prescribed frequencies may be used except alinearly polarized log periodic dipole an
46、tenna or circularly polarized conical spiralantenna. Procedures are written assuming use of aperture antennas for highfrequency plane wave measurements. An isolator is usually used between thesource and its antenna to minimize variation of power between reference and testmeasurements.E Well shielded
47、 coaxial cable such as flexible semi-rigid coaxial cable, RG-214 orRG-223, shall be used.E1851 154expected, determine the penetration points and correct the identified leakage points. Repeat the receiving equipment couplingmeasurements until negligible levels are maintained.9.3.3 Perform a noise mea
48、surement with the following equipment setup. Place the receiving antenna and equipment inside theenclosure and turn off the transmitting antenna placed outside the enclosure (see Fig. 4). The receiving antenna can be placedoutside the enclosure. When this is done an attenuator shall be inserted betw
49、een the receiving antenna and receiving equipment,and it shall be set to a shielding effectiveness level of the enclosure being tested. Measure the noise level at each frequency to beused for testing.9.3.4 After noise levels have been found negligible (or the test equipment has been modified to make the penetration negligible),position the transmitting and receiving antennas in accordance with the procedures detailed in Section 1011. For each location, usethe receiving antenna as a probe to locate areas of maximum penetration. Alternatively, a commercial le
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