Introduction to Electromagnetic Compatibility Course Sampler

1. Professional Development Short Course On:
Introduction to Electromagnetic Compatibility
Instructor:
Dr. William G. Duff
ATI Course Schedule: http://www.ATIcourses.com/schedule.htm
ATI's Space Based Radar: http://www.aticourses.com/introduction_emi.htm

2. Introduction to EMI / EMC
Summary February 24-26, 2009
This three day course is designed for technicians,
operators and engineers who need an understanding of Beltsville, Maryland
Electromagnetic Interference (EMI)/Electromagnetic
Compatibility (EMC) methodology and concepts. The $1490 (8:30am - 4:30pm)
course provides a basic working knowledge of the "Register 3 or More & Receive $10000 each
principles of EMC. Off The Course Tuition."
The course will provide real world examples and
case histories. Computer software will be used to
simulate and demonstrate various concepts and help to
bridge the gap between theory and the real world. The
computer software will be made available to the
attendees. One of the computer programs is used to
design interconnecting equipments. This program
demonstrates the impact of various EMI “EMI mitigation
techniques" that are applied. Another computer
program is used to design a shielded enclosure. The
program considers the box material; seams and
gaskets; cooling and viewing apertures; and various Course Outline
"EMI mitigation techniques" that may be used for 1. Examples Of Communications System. A
aperture protection. Discussion Of Case Histories Of Communications
There are also hardware demonstrations of the System EMI, Definitions Of Systems, Both Military
effect of various compromises on the shielding And Industrial, And Typical Modes Of System
effectiveness of an enclosure. The compromises that
are demonstrated are seam leakage, and a conductor Interactions Including Antennas, Transmitters And
penetrating the enclosure. The hardware Receivers And Receiver Responses.
demonstrations also include incorporating various "EMI 2. Quantification Of Communication System
mitigation techniques" and illustrating their impact. EMI. A Discussion Of The Elements Of Interference,
Including Antennas, Transmitters, Receivers And
Instructor Propagation.
Dr. William G. Duff (Bill) is the President of 3. Electronic Equipment And System EMI
SEMTAS. Previously, he was the Chief Concepts. A Description Of Examples Of EMI
Technology Officer of the Advanced Coupling Modes To Include Equipment Emissions
Technology Group of SENTEL. Prior to And Susceptibilities.
working for SENTEL, he worked for 4. Common-Mode Coupling. A Discussion Of
Atlantic Research and taught courses Common-Mode Coupling Mechanisms Including
on electromagnetic interference (EMI)
and electromagnetic compatibility Field To Cable, Ground Impedance, Ground Loop
(EMC). He is internationally recognized And Coupling Reduction Techniques.
as a leader in the development of engineering 5. Differential-Mode Coupling. A Discussion
technology for achieving EMC in communication and Of Differential-Mode Coupling Mechanisms
electronic systems. He has 42 years of experience in Including Field To Cable, Cable To Cable And
EMI/EMC analysis, design, test and problem solving for Coupling Reduction Techniques.
a wide variety of communication and electronic
systems. He has extensive experience in assessing 6. Other Coupling Mechanisms. A Discussion
EMI at the equipment and/or the system level and Of Power Supplies And Victim Amplifiers.
applying EMI suppression and control techniques to 7. The Importance Of Grounding For
"fix" problems. Achieving EMC. A Discussion Of Grounding,
Bill has written more than 40 technical papers and Including The Reasons (I.E., Safety, Lightning
four books on EMC. He also regularly teaches Control, EMC, Etc.), Grounding Schemes (Single
seminar courses on EMC. He is a past president of the Point, Multi-Point And Hybrid), Shield Grounding
IEEE EMC Society. He served a number of terms as a
member of the EMC Society Board of Directors and is
And Bonding.
currently Chairman of the EMC Society Fellow 8. The Importance Of Shielding. A Discussion
Evaluation Committee and an Associate Editor for the Of Shielding Effectiveness, Including Shielding
EMC Society Newsletter. He is a NARTE Certified EMC Considerations (Reflective And Absorptive).
Engineer. 9. Shielding Design. A Description Of
Shielding Compromises (I.E., Apertures, Gaskets,
What You Will Learn Waveguide Beyond Cut-Off).
• Examples of Communications Systems EMI. 10. EMI Diagnostics And Fixes. A Discussion
• Quantification of Systems EMI. Of Techniques Used In EMI Diagnostics And Fixes.
• Equipment and System EMI Concepts.
11. EMC Specifications, Standards And
• Source and Victim Coupling Modes. Measurements. A Discussion Of The Genesis Of
• Importance of Grounding. EMC Documentation Including A Historical
• Shielding Designs. Summary, The Rationale, And A Review Of MIL-
• EMI Diagnostics. Stds, FCC And CISPR Requirements.
• EMC/EMI Specifications and Standards.
52 – Vol. 96 Register online at www.ATIcourses.com or call ATI at 888.501.2100 or 410.956.8805

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4. Historical EMI/E3-Related Incidents
Operation Restore Democracy (Haiti-1995)
• Air wings of USS America & USS Eisenhower
replaced with men & helicopters of 10th Pershing II Nuclear Missile (Germany)
Infantry Div. and 75th Ranger Regiment. • Missile motor exploded during routine
• Army aircraft not designed or tested for carrier maintenance
operation, carriers required to turn off almost all • Electrostatic discharge identified as the
communications and radar surveillance systems. cause
• 3 dead
USS Forrestal (Vietnam -1969)
• ZUNI rocket inadvertently launched by a ship radar
• 134 dead
• 27 aircraft destroyed
• $72M damage to ship ($335M in 2000 dollars)
• Largest Naval loss of life since WW II
Blackhawk Helicopter (Germany and USA - 1987)
• Several potentially fatal incidents and a fatal crash HMS Sheffield (Falkland Islands -1982)
• Suspected cause was interference from high Courtesy of Jose Reza
• Hit by undetected EXOCET missile
power radio transmitters • EMI caused degradation of surveillance
• Entire fleet grounded for 3 months during radar
investigation • 21 dead,
• Extensive test and retrofit program necessary • Ship sank 4 days later

5. ELECTROMAGNETIC ENVIRONMENT
EFFECTS (E3)
Performance degradation of receiver signal
processing circuits
Erroneous or inadvertent operation of
electromechanical equipments, electronic
circuits, components, ordnance, etc.
Burnout or voltage breakdown of
components, antennas, etc.

6. ELECTROMAGNETIC ENVIRONMENT
EFFECTS (E3) CONTINUED
Unintentional denotation or ignition of
electroexplosive devices, flammable
materials, etc.
Personnel Injuries

7. ELEMENTS OF EMI
SOURCES VICTIM OF
OF EMI COUPLING
EMI

8. EMI CULPRIT AND VICTIM
EMI
CULPRIT
Source
VICTIM
Signal Signal
Source Receiver
COUPLING PATH

9. CONDUCTED OR RADIATED COUPLING
SOURCE COUPLING VICTIM

10. PRIMARY EMI INTERACTIONS
EMI SOURCE
EMI SOURCE PRIMARY COUPLING
PRIMARY COUPLING EMI VICTIM
EMI VICTIM
(EMITTER)
(EMITTER) MECHANISM
MECHANISM (RECEPTOR)
(RECEPTOR)
RADIATED
RADIATED RECEIVERS
RECEIVERS
ANT-ANT
ANT-ANT
TRANSMITTERS
TRANSMITTERS
RADIATED
RADIATED ELECTRONIC
ELECTRONIC
ANT-CABLE
ANT-CABLE EQUIPMENT
EQUIPMENT
ANT-CASE
ANT-CASE
RADIATED
RADIATED
CABLE-ANT
CABLE-ANT RECEIVERS
RECEIVERS
CASE-ANT
CASE-ANT
RADIATED
RADIATED
ELECTRICAL &
ELECTRICAL &
CABLE-CABLE
CABLE-CABLE
ELECTRONIC
ELECTRONIC CABLE-CASE
CABLE-CASE
EQUIPMENT
EQUIPMENT
CASE-CABLE
CASE-CABLE
CASE-CASE
CASE-CASE ELECTRONIC
ELECTRONIC
EQUIPMENT
EQUIPMENT
CONDUCTED
CONDUCTED
POWER LINES
POWER LINES
SIGNAL LINES
SIGNAL LINES
GROUND
GROUND

11. EXAMPLES OF NARROWBAND EMI UNITS
Conducted
Power Voltage Current
W V A
dBW dBV dBA
dBm dBμV dBμA
Radiated
Power Density Field Strength Magnetic Field (H) Magnetic Flux Density (B)
W/m2 V/m A/m Tesla (Weber/m2)
dBW/m2 dBv/m dBA/m Picotesla (pT)
dBm/m2 dBμV/m dBμA/m dBpT

12. EXAMPLES OF BROADBAND EMI UNITS
Conducted
Power Voltage Current
dBm/kHz dBμV/MHz dBμA/MHz
Radiated
Power Density Field Strength Magnetic Field (H) Magnetic Flux Density (B)
dBm/m2/kHz dBμV/m/MHz dBμA/m/MHz dBpT/MHz

13. Filter Affects on a Pulse
Vin
V1
Tin
Vin T1
F1
Tin
V1 = F1TinVin
T1 = 1/F1

14. Electric-Field Strength vs.
Transmitter Distance and ERP*

15. Walkie Talkie Crashes Equipment

16. EMI MITIGATION FOR
OTHER SYSTEMS
Radiated EMI Mitigation
• Shielding
• Circuit Design
• Cable Selection and Layout
Conducted EMI Mitagation
• Grounding
• Filters, Ferrites, Isolation Transformers, Optical
Isolators, etc.

17. TWO-BOX EMI SEVERAL MILLION COMBINATIONS!
MANY WITH AN INFINITE RANGE OF VARIABLES.

18. MANIFESTATIONS
Multiple Sites • Battle Force - EME
Site • Aircraft, Ship or Building
System • Fire-Control Radar, Control System
Subsystem • Equipment Racks, Consoles
Equipment • R.F. Receiver, Medical Instrument
Mother
• Main Distribution to PCB
Board
PCB • Cards to Hold DIPS Components
Component • DIPS, CHIPS, Relays

19. COUPLING
Conducted power or signal cable coupling
Common-ground impedance common-mode coupling
Field-to-Cable or Cable-to-Field common-mode coupling
Field-to-cable or Cable-to-Field differential-mode coupling
Cable-to-Cable differential-mode coupling
Case Radiation-Case Penetration

20. CONDUCTED EMI
“EMI always start out at the culprit and
ends up at the victim as a conducted
signal regardless of what goes on
between these two points!”

21. Illustration of Common Mode Currents
CMC 1
Power Source Load
CMC 2
CMC
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
Metallic Structure
Figure 4. Illustration of Common Mode Currents

22. Illustration of Differential Mode Currents
DCM1
Power Source Load
DCM2
Figure 3. Illustration of Differential Mode Currents

23. Illustration of Common and Differential Mode Currents
CMC 1 DMC 1
Power Source Load
CMC 2 DMC 2
CMC
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
Metallic Structure
Figure 5. Illustration of Common and Differential Mode Currents
Illustration of Common and Differential Mode Currents
Illustration of Common and Differential Mode Currents

24. Common Mode Currents Resulting From
Distributed Capacitance to Ground
CMC 21
Power Source Load
CMC 21
CMC1
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
Metallic Structure
Figure 6. Common Mode Currents Resulting From
Distributed Capacitance to Ground

25. Common Ground Impedance Common Mode EMI
CMC
Power Source Load
CMC
EMI EMI'
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
Metallic Structure
Figure 10. Common Ground Impedence Common Mode EMI

26. Controlling Conducted EMI
Source Victim
Power Supplies Analog Equipment
Motors Conducted Digital Equipment
Inductive Loads EMI Video Display
High Level Analog Recorders
Digital Signals Instruments
Transmitters Sensors
EM Environment Control Systems
Receivers
Applicable EMI Control Techniques
Differential Mode Common Mode (Ground Loop)
Power Signal Power Signal
Filter Filters Filters Filter
Ferrites Ferrites Ferrites Ferrite
Isolation Transformers Isolation Transformers Isolation Transformers Isolation Transformers
Translent Suppressors Translent Suppressors Balanced Systems Balanced Circuit
Float Float
Inductor in Ground Inductor in Ground
Optical Isolator

27. WHAT IS GROUND ?
• SIGNAL RETURN?
• CHASSIS REFERENCE?
• SAFETY WIRE REFERENCE?
• EARTH REFERENCE?

28. GROUNDING HIERARCHY

29. GROUNDING CONDUCTOR
IMPEDANCE VS. FREQUENCY

30. Using Ferrites to Absorb
Common-Mode EMI

31. PRINCIPAL RADIATION SOURCES ON
PRINTED CIRCUIT BOARD
Radiation from
IC dips
Logic families
clock rates
• Large single-layer board
• PCB card cage with back plane
• Multi-layer board
Radiation from
ribbon cables

32. MAGNETIC FIELDS FROM A TWISTED
PAIR OF CONDUCTORS (TRANSPOSITION)
Area 2 Area 1
I1 I2
V ΔV2 ΔV1 RL
I2 I1

33. REPRESENTATION OF SHIELDING PHENOMENA
FOR PLANE WAVES
Ey Inside of Enclosure
Hz
Incident WaveA Ey Transmitted Wave
Ey
B
H
Ey Attenuated
Hz Incident
Hz
Ey Hz
Reflected Wave
Wave Internal Reflecting
Outside World Metal Wave
Barrier

34. PRINCIPAL BOX SHIELDING COMPROMISES
Holes or Slots Screw Spacing
Cover Plate for Convection Cooling = Slot Radiation
for Access
Status
Indicator
Lamp
Forced Air
Cooling
Panel Meter
Potentiometer
Connectors
Fuse
Switch

35. PP47645A
Some System EMC Fix Applications
PP47645A

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