SAE ARP958E-2021 PDF

Full title and description

SAE ARP958E-2021 — Electromagnetic Interference Measurement Antennas; Calibration Method. An SAE Aerospace Recommended Practice (Revision E, 2021) that defines a standardized, economical procedure for checkout and calibration of antennas used for electromagnetic interference (EMI) / electromagnetic compatibility (EMC) radiated emissions measurements. The document emphasizes 1 m test geometry in shielded rooms (typical for military/aerospace testing), provides calibration techniques for broadband and specialty antennas, and updates procedures to reflect modern instrumentation and hybrid antenna calibration.

Abstract

This recommended practice describes methods to determine antenna factors and perform routine calibration and verification of EMI measurement antennas (biconical, horn, monopole, small loop, hybrid and related types) when used primarily for 1 m shielded-room emissions testing. It provides step-by-step calibration procedures, recommended test geometry, and guidance on instrumentation and measurement technique while noting limitations (for example, the influence of the shield room is not treated). Revision E (2021) adds instructions for hybrid antennas, clarifies procedures, and incorporates modern measurement equipment considerations.

General information

• Status: Revised (Revision E).
• Publication date: September 1, 2021.
• Publisher: SAE International.
• ICS / categories: 33.100 Electromagnetic compatibility (EMC); relevant subcategory: 33.100.10 Emission.
• Edition / version: ARP958E (Revision E, 2021). Historical issue: originally issued March 1, 1968; prior revisions A–D through 2003.
• Number of pages: 30 pages.

Scope

Provides a standardized calibration method for antennas used to measure radiated emissions in a 1 m test geometry inside shielded rooms. The procedure targets determination of antenna factors and antenna verification for commonly used EMI measurement antennas and is intended for situations where a test antenna measures a source 1 m away (a typical military/aerospace test configuration). The standard does not attempt to quantify the influence of the shielded room itself and is not intended as a general method for unknown distributed sources, although the calibration technique uses a second antenna to approximate distributed-source behavior.

Key topics and requirements

• Definitions and test geometry for 1 m calibration in shielded-room environments.
• Procedures to determine antenna factor (AF) across frequency for broadband and tuned antennas.
• Calibration methods and checkout procedures for antenna types including biconical, horn, monopole, small loop, and hybrid antennas.
• Specific guidance for loop antenna calibration with 1 m separation from the device under test (added in earlier revisions and refined here).
• Inclusion of modern instrumentation considerations (receivers, spectrum analyzers, preamplifiers) and recommended measurement practices (added in Revision E).
• Uncertainty-awareness and repeatability recommendations for routine calibration/verification.
• Practical test setup, alignment, and fixture recommendations to produce consistent antenna-factor data for emissions testing.

Typical use and users

Primary users are EMC/EMI engineers, calibration laboratory personnel, test-house operators, antenna manufacturers, aerospace and defence test teams, and compliance engineers who perform or oversee radiated emissions measurements using 1 m test geometries. The practice is used to calibrate and verify measurement antennas prior to compliance testing (for example test programs referencing military or industry EMC requirements).

Related standards

Commonly referenced documents and related standards include ANSI/IEEE test-method standards and military EMC standards used for radiated-emissions measurement and antenna calibration, for example: ANSI C63.5 (antenna calibration guidance), IEEE Std 149, IEEE Std 291, SAE J551 series references, MIL-STD-461 and MIL-STD-462 (radiated emissions requirements and measurement methods). ARP958E builds on earlier ARP958 revisions (A–D) and aligns with recognized EMC measurement practices.

Keywords

EMI, EMC, antenna calibration, antenna factor, biconical, horn antenna, monopole, loop antenna, hybrid antenna, shielded room, 1 m test, radiated emissions, SAE ARP958E, military/aerospace testing.

FAQ

Q: What is this standard?

A: SAE ARP958E-2021 is an SAE Aerospace Recommended Practice that specifies a standardized calibration and checkout method for electromagnetic interference (EMI) measurement antennas used primarily in 1 m shielded-room radiated-emissions testing.

Q: What does it cover?

A: It covers procedures to determine antenna factors and perform calibration/verification for broadband and specialty antennas (biconical, horn, monopole, small loop, hybrid), recommended test geometry and equipment considerations, and practical steps for repeatable calibration measurements. It intentionally does not model the influence of the shield room itself nor is it a method for characterizing unknown distributed emissions sources.

Q: Who typically uses it?

A: EMC test laboratory engineers, calibration labs, antenna manufacturers, aerospace and defense test teams, and compliance engineers performing radiated-emissions testing in 1 m configurations.

Q: Is it current or superseded?

A: The document is Revision E, published September 1, 2021. It is the current Revision (E) of ARP958 as published by SAE International; earlier revisions include A–D (historically back to the original 1968 issue). Users should verify whether a newer revision exists when planning work (this description reflects the ARP958E status published 2021).

Q: Is it part of a series?

A: Yes. ARP958 has multiple historical revisions (ARP958, ARP958A through ARP958D, and ARP958E). It is typically used alongside related EMC and antenna measurement standards (ANSI/IEEE test standards and applicable military standards such as MIL-STD-461/462) that define test requirements and limits.

Q: What are the key keywords?

A: Antenna calibration, antenna factor, EMI, EMC, radiated emissions, shielded room, 1 m test, loop antenna, biconical, horn, hybrid antenna.