MIL-STD-461 EMI and EMC standards

Quick look:

• Testing standards for electromagnetic compatibility, specifically electromagnetic emissions and susceptibility that can cause interference (EMI) to other equipment or be vulnerable to interference from other equipment
• Determines interoperability with other equipment; known as electromagnetic compatibility (EMC) testing
• Adopted in 1967 with many updates and additions since
• Applicable for DoD applications

About MIL-STD-461

For the Department of Defense (DoD), specifying a computer’s electromagnetic interference (EMI) and its electromagnetic compatibility (EMC) is a vital indicator on how well the computer will operate within many “noisy” environments. MIL-STD-461 breaks down the EMI requirements for a wide range of applications, from trucks and ships to aircraft and fixed installations, as well as the various requirements within an application (e.g., above deck vs. below deck on a Navy ship). There is also an opportunity to tailor the requirements to particular applications.

Since the 1990s, the DoD has encouraged the use of commercial off-the-shelf (COTS) components wherever possible. In certain situations though, military standards such as MIL-STD-461 must be enforced when the system needs to coexist with other equipment such as powerful transmitters and highly sensitive receivers. Oftentimes, commercial components and computers require upgrades or ruggedization to meet these rigorous military demands.

MIL-STD-461 tests

Conducted emissions

• CE101 – Power & Interconnecting Leads
• CE102 – Power & Interconnecting Leads
• CE103 – Antenna Terminals

Conducted susceptibility

• CS101 – Applicable to Power Input Leads that obtain power from other sources not part of the computer, including those that are rechargeable.
• CS103 – Antenna Port, Intermodulation
• CS104 – Antenna Port, Signal Rejection
• CS105 – Antenna Port, Cross Modulation
• CS109 – Structure Current
• CS114 – Bulk Cable Injection
• CS115 – Bulk Cable Injection, Impulse Excitation
• CS116 – Damped Sinusoid Transients – I/O & Power Cables

Radiated emissions

• RE101 – Magnetic Field
• RE102 – Electric Field
• RE101 – Antenna Spurious & Harmonic Outputs

Radiated susceptibility

• RS101 – Magnetic Field
• RS103 – Electric Field
• RS105 – Electromagnetic Pulse Field Transient

Complying with MIL-STD-461

Equipment that meets MIL-STD-461 standards will not be impacted by electromagnetic interference or disrupt other devices. Although the most modest EMC requirements are not much different from commercial requirements, most applications are decidedly harsh.

Crystal Group routinely tests and complies to CE102 and RE102 when a generic requirement for MIL-STD-461 compliance is levied on a system. Else the system is required to comply with FCC regulations and limits.

When specifying MIL-STD-461, which goes beyond the basic criteria described above, it’s necessary to specify the expected testing categories and limit lines. This takes into consideration the actual exposure in the application to limit schedule delays and unnecessary costs.

Testing at Crystal Group

If you have questions about our testing or our rugged product line, please contact us or call us at: 800.378.1636.