MIL-STD-461 establishes the requirements for the control of electromagnetic interference (emission and susceptibility) characteristics of electronic, electrical, and electromechanical equipment and subsystems designed or procured for use by activities and agencies of the Department of Defense (DoD).

Table 4-1 shows the emission and susceptibility requirements listed in MIL-STD-461. The type of test required is dependent upon the platform. Conducted Emissions tests (CE101, CE102, CE106) are used to verify that electromagnetic emissions conducted via the wiring and antenna terminal from a device under test (DUT) do not exceed the specified requirements.

Conducted Susceptibility tests (CS101, CS103, CS104, CS105, CS109, and CS114-116) are used to verify that the DUT can withstand radio frequency (RF) signals coupled onto the leads (cables, wires). These include intermodulation products and spurious responses that may cause undesired signals at the DUT. RE101, RE102, and RE103 are used to verify that electric field
emissions from the DUT, electrical interface, associated cabling, and radiated spurious/harmonic output do not exceed specified limits. RS101, RS103, and RS105 are used to verify the ability of the DUT and its associated cabling to withstand radiated magnetic, electric, and transient electromagnetic fields. These are to be tested in a range of frequencies which can be as low as 30 Hz to as high as 40 GHz. Table 4-2 shows the frequency ranges for susceptibility scanning.

General test preparation tips
1. Create a test plan for each test required, including details on how to collect the data.

2. Determine the amount of time needed toconduct the test and schedule the appropriate lab time. Because of the limited number of U.S. labs which can perform EMI testing to MIL-STD-461, reserving lab time can be challenging. Demand for this service is high.

3. Forward a copy of your test plan to the lab so that they have a better idea of what you are trying to accomplish. The lab will review your test plan and provide valuable feedback regarding their capabilities and how your test plan may be improved. You may need to make revisions.

4. Confirm with the lab if the equipment you need is available. The lab may not have special test/mounting fixtures, test cables, or data recording equipment. You may need to bring your own.

5. Avoid the unexpected at the lab by simulating and testing as much as possible beforehand. This will give you a rough idea of whether your equipment will pass, allowing time for adjustments.

Each individual test can take as little as a half day or as much as several months. Some labs charge per day rather than by the hour. Costs of $1500/day are typical. When scheduling your lab service, try to group together similar tests or tests which use the same lab equipment. This will reduce setup and calibration time. Setup itself can take several hours, so be sure to include adequate setup time in your schedule. In conclusion, always plan ahead so that your test can run as smoothly as possible without unexpected delays or the need to return to the facility for re-testing.