MIL-STD-461 is the standard that defines the test limits, test levels, and test procedure for various electromagnetic phenomena for electronic equipment used by the U.S. Army, Navy, and Air Force on all platforms (ground, sea, and air). MIL-STD-461F is the latest version. Following are answers to common questions about this often-utilized military EMC standard.
Where can I find MIL-STD-461 and how much does it cost?
The standard is free and approved for public release. It can be downloaded from a number of sites, but we recommend using the official U.S. Defense Logistics Agency (DLA) ASSIST site. This site requires registration and a wait for approval.
What is included in MIL-STD-461?
Test methods cover electromagnetic emissions, which are an unintended, but unavoidable byproduct of every electronic device, as well as electromagnetic susceptibility, which is a measure of the equipment under test’s (EUT) ability to withstand electromagnetic disturbances.
Test methods include specific types of conducted, radiated, transient, and continuous emissions and susceptibility tests. See a full list of test methods on MET’s Military EMC Testing page.
The first few sections define general aspects of the standard and testing, such as terminology, test facilities, test equipment, setup of the EUT, applicable tests for equipment to be used on various platforms, etc.
Section 5 contains a test procedure for each test method, which defines the test equipment needed, instructions for setup, and a procedure for how to conduct the test.
Is compliance with MIL-STD-461 mandatory?
MIL-STD-461 is usually only required when part of a specific military contract between the U.S. military and an electronic equipment manufacturer.
The contract would specify the specific test methods within -461 which need to be performed and passed by the equipment being built for the military.
MIL-STD-461 testing is sometimes voluntarily performed by electronic equipment manufacturers for marketing purposes, to attract possible military contracts and/or for quality purposes, to ensure a rugged design.
I want to voluntarily perform MIL-STD-461 testing and am not worried about my EUT’s susceptibility to electromagnetic disturbances. What are the best test methods for determining compliance with the standard’s electromagnetic emissions requirements?
CE102 and RE102 are the most applicable test methods for this.
This will ensure that the EUT does not cause interference to other electronic equipment operating from the same power source, since the emissions can conduct along the supply lines.
A special piece of test equipment called a line impedance stabilization network (LISN) is connected in series with each conductor of the input power lines to the EUT.
The LISN establishes a 50 Ohm impedance on the power line and has a coaxial measurement port, which allows for connection to a 50 Ohm spectrum analyzer for measurement of the RF emissions.
The EUT is exercised in a way typical of its normal use and the emissions are compared to the limit. If CE102 emissions exceed the limits, the tests are considered not compliant.
RE102, radiated emissions, electric field, 10 kHz to 18 GHz, is performed to verify that electric field emissions from the EUT and its associated cabling do not exceed specified requirements.
This will ensure that radiated emissions from the EUT do not cause interference to other electronic equipment operating nearby.
The EUT and test antenna are set up within a shielded test enclosure, which is internally lined with RF absorbent material.
The shielded enclosure prevents RF ambient noise from entering the test area, while the RF absorbent material reduces RF reflections from the metallic chamber walls, allowing for accurate radiated RF measurements of the EUT emissions with a test antenna.
The test antenna is connected through coaxial cable and chamber wall bulkhead connectors to the spectrum analyzer outside the test chamber.
The EUT is exercised in a way typical of its normal use and the emissions are compared to the limit. If RE102 emissions exceed the limits, the tests are considered not compliant.
For MIL-STD-461 testing for marketing purposes only, does MET issue a test report?
MET can issue a test report and a one-page certificate upon completion of testing.
The test report and certificate would not guarantee acceptance of the product by the U.S. military. However, you are free to use your engineering judgment to make claims of compliance for similar projects, based on the test report and certificate provided.
MET Labs has a reputation for high quality test results and our test reports will increase the credibility of your marketing claims.
Request a free quotation for MIL-STD testing for military or marketing requirements.