Whitepaper
Basic Elements of MIL-STD-461
This Curtiss-Wright Defense Solutions white paper provides an accessible overview of MIL-STD-461, the U.S. Department of Defense standard governing EMI emission and susceptibility requirements for military electronic equipment and subsystems. It explains the background of EMI and EMC, noting that high-frequency signals effectively turn every conductor into a potential antenna. The paper clarifies that MIL-STD-461 applies at the subsystem and equipment level rather than to individual circuit cards or modules, and it notes that older revisions of the standard remain relevant because legacy military platforms continue to be serviced under the version in effect when they were originally designed. The alphanumeric test designation system is explained — CE, RE, CS, and RS codes covering conducted and radiated emissions and susceptibility — and a full table of MIL-STD-461F requirements is provided alongside a platform applicability matrix showing which tests apply to surface ships, submarines, Army and Navy and Air Force aircraft, space systems, and ground installations. The paper briefly addresses commercial comparisons, noting that FCC Part 15 requirements are generally less stringent and that RTCA DO-160 revisions C through E are often acceptable for military aircraft. Design considerations for COTS equipment focus on metal shielding for radiated emissions, power supply pre-filtering for conducted susceptibility, and the importance of taking a holistic view of filter networks to avoid unintended interactions. The document closes with a summary of Curtiss-Wright's chassis and backplane product lines and associated engineering services.