MIL-STD-285: Military Testing of Attenuation Measurements For Enclosures

MIL-STD-285 is a military standard that outlines the requirements for the measurement of the shielding effectiveness of electrical and electronic enclosures. The standard provides guidelines for the testing of these enclosures, ensuring that they provide adequate protection from electromagnetic interference (EMI) and radio frequency interference (RFI).

Shielding effectiveness is an important aspect of the development and manufacture of electronic and electrical equipment, as it helps to determine the ability of an enclosure to shield against unwanted electromagnetic emissions. The MIL-STD-285 standard specifies the test methods and procedures that should be used to measure shielding effectiveness, as well as the equipment and materials required for the tests.

Summary of MIL-STD 285 Certification Testing for Enclosures

One benefit of MIL-STD-285 shielding effectiveness testing is that it helps to ensure the reliability and functionality of electronic and electrical equipment in the presence of electromagnetic interference. By providing a standardized and consistent approach to the testing of enclosures, the standard helps to ensure that electronic equipment is able to operate effectively and securely, even in challenging electromagnetic environments.

Another benefit of the MIL-STD-285 standard is that it provides a common reference for the testing and measurement of shielding effectiveness, which helps to ensure the compatibility and interoperability of electronic equipment across different platforms and systems. The standard also helps to ensure the reliability and security of military systems and networks, by helping to prevent the infiltration of unwanted electromagnetic emissions that could compromise the integrity of these systems.

The results of these tests are critical in helping to ensure the reliability and functionality of electronic and electrical equipment, and in maintaining the safety and security of the systems they support.

Scope of Military Shielding Effectiveness Standard Testing

The requirements of the test setup for MIL-STD-285 testing are relatively straight forward. The arrangement of signal sources measuring equipment, pick-up devices, and shielded enclosures are all detailed within the standard. All power lines, RF cables, and other utilities entering the shielded enclosure must be in place when tests are conducted. Special care should be taken to make measurements in the vicinity of utility entrances, doors, and access panels.

Electromagnetic Barrier

A topologically closed surface created to prevent or limit fields and conducted transients from entering the enclosed space. The electromagnetic barrier consists of the shield and POE treatments. This barrier encloses the protected volume and special protective volumes if required.

Electromagnetic Closure

A treatment to prevent excessive electromagnetic field leakage at an aperture point of entry. Examples of closure techniques at a seam between two metal plates include welding, brazing, or soldering and metal-to-metal contact under pressure applied with a mechanical fastening.

Mission-Critical Equipment

All equipment required to directly support a critical mission, success, or failure of which could affect the outcome of the battle. Mission-critical equipment often refers to all communications-electronics and support equipment that must be protected in order to perform critical trans- and post-HEMP attack missions.

Point-of-Entry (POE)

A location on the electromagnetic barrier where the shield is penetrated and energy may enter the protected volume. This will occur unless an adequate POE protective device is provided. POEs are classified as aperture POEs or penetrating conductors according to the type of penetration. They are also classified as architectural, mechanical, structural, or electrical POEs according to the engineering discipline in which they are usually encountered.

MIL-STD 285 Shielding Effectiveness Test Procedures

The testing process involves exposing the enclosure to an electromagnetic field and measuring the amount of electromagnetic energy that penetrates the enclosure. The shielding effectiveness is then calculated as the ratio of the electromagnetic energy inside the enclosure to the electromagnetic energy outside the enclosure.

The results of the testing are used to determine the effectiveness of the enclosure in blocking unwanted electromagnetic emissions, and to identify areas where improvements can be made.

Expert MIL-STD 285 Regulatory Compliance

In conclusion, MIL-STD-285 shielding effectiveness testing is an essential aspect of the development and manufacture of electronic and electrical equipment. The standard provides a consistent and reliable approach to the testing of enclosures, ensuring that they provide adequate protection from electromagnetic interference and radio frequency interference.

Keystone Compliance has the capabilities to test any size of enclosure to MIL-STD-285. We have tested large items such as entire on-site installation buildings and small items that can be easily transported to our lab.

In addition to MIL-STD-285 compliance testing, Keystone has a full scope of expertise including environmental and package testing such as cold chain, accelerated aging, and temperature. Our team strives to give our customers more time and energy on product development instead of testing. Lastly, Keystone has a full lab of test equipment which permits us to provide short lead times on scheduling.

Are you ready to partner with Keystone Compliance to determine the shielding effectiveness of your product when tested to the requirements of MIL-STD 285? Let’s get started!

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