ARP958E Electromagnetic Interference Measurement Antennas; Calibration Method



Issuing Committee
This SAE Aerospace Recommended Practice outlines a standardized and economical method for the checkout and calibration of electromagnetic interference measurement antennas. Its application is for use when measuring a source 1 m from the antenna in a shield room. This is the typical distance used in performing military EMC testing. The influence of the shield room on the measured field strength is not considered. This standard does not address the measurement of emissions from an unknown distributed source, yet it attempts to resemble reality by using another antenna, in the calibration method, that represents a distributed source. This document presents a technique to determine antenna factors for antennas used primarily in performing measurements in accordance with References 2.1 and 2.2. The purpose of Revision B was to include the calibration of other antennas, such as biconical, horn, monopole and small loop antennas that are also specified for use in these same references. Revision D includes a specific procedure for loop antennas that are separated by 1 m from the device under test. Revision E adds the inclusion of modern instrumentation, instruction on how to calibrate the hybrid antenna, and attempts to improve upon the clarity of this document for the user.
This document was fully revised to bring the content and formatting up-to-date. The following major improvements were also incorporated as part of this revision:
  1. 1
    Defined how to calibrate hybrid biconical log antennas. Documented the measurement distance position on each antenna.
  2. 2
    Incorporated the three-antenna method and compared with the two “identical” antenna method, particularly where the antenna is of the same type (e.g., biconical) but not the same manufacturer or model. At least two 1:1 (50 Ω) baluns should be paired, and two 4:1 (200 Ω) baluns.
  3. 3
    Corrected errors in the ECSM equations.
  4. 4
    Clarified the content in Appendix C and standardized globally.
  5. 5
    Added near-field formulation to derive Antenna Factor (AF) from the site insertion loss between a pair of antennas as it relates to measurement uncertainty.
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SAE International Recommended Practice, Electromagnetic Interference Measurement Antennas; Calibration Method, SAE Standard ARP958E, Revised September 2021, Reaffirmed February 2003, Issued March 1968,
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Sep 1, 2021
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Recommended Practice