What is it?
MIL-STD-461 outlines electromagnetic compatibility (EMC) testing requirements for military equipment, as maintained by the United States Department of Defense. MIL-STD-461 testing essentially offers an added layer of electromagnetic interference (EMI) protection for military electronic and electrical systems, making sure that any system tested against MIL-STD-461 requirements is more likely to accept interference received from other devices and not interfere with other devices.
With MIL-STD-461 being a common requirement for military programs and systems, companies that specialize in manufacturing EMC test equipment, such as Com-Power Corporation, are helpful in advising companies on what test equipment is needed in order to make sure that their products are MIL-STD-461 compliant.
Development and Evolution
The first US military EMI standard, SCL-49, was published in 1934 by the Army Signal Corps and protected radio receivers in vehicles from interference, simply requiring the vehicle operation not disrupt radio reception. However, with the increased use of radio communications in the years following, SCL-49 was superseded by another standard in 1942, starting the trend of standards adapting to the evolution of technology.
By the 1960's, the US Department of Defense enacted the Defense Radio Frequency Compatibility Program (later called the Electromagnetic Compatibility Program) that put a focus on internal EMC being taken into account during the research and development phase of electronic and electrical systems. The program resulted in MIL-STD-461 being adopted in 1967, and quickly revised with MIL-STD-461A being issued in 1968. Throughout the years, the revisions have been constant, with the most recent update, MIL-STD-461G, being issued in 2015. There are now nineteen different MIL-STD-461 tests, which address conducted emissions, conducted susceptibility, radiated emissions and radiated susceptibility.
With MIL-STD-461 requiring relatively demanding EMC requirements, devices which are compliant with MIL-STD-461 are normally well-positioned to meet standards as set by other EMC regulating agencies, such as the FCC and FAA. This means that, while MIL-STD-461 compliance is not required outside of the US military, other military and civilian organizations use it as guidance when they are conducting their own research and development.
As the military has continued to adopt more and more electrical and electronic systems working in close proximity to each other, and the fact that some of those systems function in very critical circumstances, it is imperative that military personnel are assured that their systems won't be disrupted by EMI. Systems being used that are not MIL-STD-461 run the risk of causing mission disruption, mission failure or other catastrophic events that could affect the security of military personnel as well as national security.
Electronic warfare (EW) has been around since the beginning of the 20th century but has become much more sophisticated as technology has advanced. Essentially EW means the weaponization of the electromagnetic spectrum. Intercepting wireless transmissions, radio jamming, radar systems, stealth aircraft and GPS jamming are all examples of EW and have been used over the last century or so by numerous militaries around the world to advance their operations. With electronic systems being such a vital part of mission readiness, proper EMC testing is necessary, and MIL-STD-461 outlines what is needed to ensure systems are compliant and mission ready.
Systems that work in close proximity to each other can be affected by EMI, or disrupt other systems, resulting in lower functioning gear, or a complete shutdown of the system(s). When dealing in extreme situations, making sure that all gear functions as it should, without affecting the systems around it, is crucial, and MIL-STD-461 is in place to make sure that electrical and electronic systems have the highest likelihood of facilitating mission readiness for the US military.
The importance of MIL-STD-461 compliance cannot be overstated when dealing with critical systems that will be used in extreme situations. No matter the organization, EMC compliance is essential in order to mitigate risks when a new product is launched, as EMI can have disastrous results. EMC test equipment manufacturers can help ensure that your product is compliant, offering test systems and knowledge that will help to make sure that whatever makes it to production and launch will function as it should, not disrupt the devices around it, and increase the chances of success, no matter the mission.