EMI / EMC in Military Systems

Systems EMC (Electromagnetic Compatibility) involves the control of EMI (Electromagnetic Interference) at the systems, facility, and platform levels (e.g. outside the box.) This three-day course provides a comprehensive treatment of EMI/EMC problems in military systems. These include both the box level requirements of MIL-STD-461 and the systems level requirements of MIL-STD-464. The emphasis is on prevention through good EMI/EMC design techniques – grounding, shielding, cable management, and power interface design. Troubleshooting techniques are also addressed in an addendum. Please note – this class does NOT address circuit boards or specific test issues. Each student will receive a copy of the EDN Magazine Designer’s Guide to EMC by Daryl Gerke and William Kimmel, along with a complete set of lecture notes.

Thinking about EMC training? The payback is there — just one extra trip to the test lab can cost you $10-20K in test and engineering time! Not to mention the additional cost of being late to market, or the cost of fixing EMI problems in the field.

• How to identify, prevent, and fix common EMI/EMC problems in military systems
• Simple models and “rules of thumb” and to help you arrive at quick design decisions (NO heavy math).
• EMI/EMC troubleshooting tips and techniques.
• Design impact (by requirement) of military EMC specifications (MIL-STD-461 and MIL-STD-464)
• EMI/EMC documentation requirements (Control Plans, Test Plans, and Test Reports)

1. Introduction. Interference sources, paths, and receptors. Identifying key EMI threats – power disturbances, radio frequency interference, electrostatic discharge, self-compatibility. Key EMI concepts – Frequency and impedance, Frequency and time, Frequency and dimensions. Unintentional antennas related to dimensions.
2.  Grounding – A Safety Interface. Grounds defined. Ground loops and single point grounds. Multipoint grounds and hybrid grounds. Ground bond corrosion. Lightning induced ground bounce. Ground currents through chassis. Unsafe grounding practice.
3.  Power – An Energy Interface. Types of power disturbances. Common impedance coupling in shared ground and voltage supply. Transient protection. EMI power line filters. Isolation transformers. Regulators and UPS. Power harmonics and magnetic fields.
4.  Cables and Connectors – A Signal Interface. Cable coupling paths. Cable shield grounding and termination. Cable shield materials. Cable and connector ferrites. Cable crosstalk. Classify cables and connectors.
5.  Shielding – An Electromagnetic Field Interface. Shielding principles. Shielding failures. Shielding materials. EMI gaskets for seams. Handling large openings. Cable terminations and penetrations.
6.  Systems Solutions. Power disturbances. Radio frequency interference. Electrostatic discharge. Electromagnetic emissions.
7.  MIL-STD-461 & MIL-STD-464 Addendum. Background on MIL-STD-461 and MIL-STD-464. Design/proposal impact of individual requirements (emphasis on design, NOT testing.) Documentation requirements – Control Plans, Test Plans, Test Reports.
8.  EMC Troubleshooting Addendum. Troubleshooting vs Design & Test. Using the “Differential Diagnosis” Methodology Diagnostic and Isolation Techniques – RFI, power, ESD, emissions.

Daryl Gerke, PE, has worked in the electronics field for over 40 years. He received his BSEE from the University of Nebraska. His experience ranges includes design and systems engineering with industry leaders like Collins Radio, Sperry Defense Systems, Tektronix, and Intel. Since 1987, he has been involved exclusively with EMI/EMC as a founding partner of Kimmel Gerke Associates, Ltd. Daryl has qualified numerous systems to industrial, commercial, military, medical, vehicular, and related EMI/EMC requirements.