AGENDA - MIL-STD-1310: SHIPBOARD EMC DESIGN PRACTICES

There has been a major explosion in the use of high speed digital systems, handheld wireless tranceivers, and other electrical and electronic equipment aboard naval vessels. All this high level RF energy introduces severe electromagnetic interference (EMI) and susceptibility problems to ship operation and performance. MIL-STD-464C has shipboard susceptibility requirements exceeding 27,000 V/m at some frequencies. To make matters worse the operational environment is highly corrosive and creates non linear junctions requiring control of hull generated interference and to minimize development cost there is increased use of commercial-off-the-shelf (COTS) equipment and non-developmental items (NDI).

MIL-STD-1310 specifies the performance requirements for shipboard bonding, grounding and shielding; identifies requirements for EMI control in the areas of hull-generated and equipment-generated EMI, hull and cable penetration EMI, and superstructure blockage/reflections; specifies requirements for protection of personnel from electrical shock, and identifies the applicable requirements for measuring the effectiveness of EMI control and safety measures. The specified requirements apply to both metal and nonmetallic hull ships and are applicable during construction, overhaul, alteration, or repair.

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1. EMI/RFI/EMC BASICS
Terms and Definitions
Time to Frequency Conversion
Acronyms Used in MIL-STD-1310G
Examples of Interference Conditions
Interference Sources
Interference Receptors
Overview of Typical EMI Levels/Coupling
Power Line Disturbances
Transients - ESD, Lightning, EMP
F.A.S.T. Analysis
Systems Emission/Immunity
Comparison of MIL-STD-461E and FCC/EU Commercial EMC Requirements
MIL-STD-464A Requirements for Commercial and NDI Equipments
MIL-STD-464A Radiated Susceptibility Requirements for USNavy Ships

2. OVERVIEW MIL-STD-1310G REQUIREMENTS
Grounding/Bonding
Hull Generated EMI
Hull and Cable Penetration EMI
Superstructure Blockage/Reflections
Equipment Generated EMI
Electrical Safety for Ungrounded Power

3. EMC SYSTEMS DESIGN FUNDAMENTALS
Conducted vs Radiated Emission
Simplified Circuit Loop Radiation Equation
Maximum Loop Area to meet emission limits
Simplified Circuit Loop Pickup Equation
Design Emphasis
Spectrum Density vs Pulse Shape
Ultra Wide Band (UWB)
Narrow Band (NB) & Broad Band (BB) Signals
Differential and Common Mode Currents

4. CABLE EMC DESIGN/INSTALLATION PRACTICES
Cables: Equipment Antennas - The Primary EMC Problem
Cable Differential/Common Mode Coupling
Field to Wire-Pair and Wire-Pair to Field
Twisted Pair
Cable Shielding
Grounding Rules for Cable Shields
Pigtails and Daisy Chains
Coaxial Cables
Connectors
Crosstalk
Conduit, Ultimate Shield
Field to Grnd Loop Coupling & Reduction
Common Mode to Diff Mode Conversion
Floating & Single Point Grounding
Balanced Line Drivers/Receivers
Series RF Inductors
Double Shielding
Shielded Transformers and Baluns
Ferrites
Optical Coupling

5. FILTER SELECTION/INSTALLATION
Basic Filter Types
Attenuation vs Frequency
Source and Load Impedance
Butterworth Low-Pass Filter
Inrush Current
Filter Mounting & I/O Isolation
Faying Surface Requirements
Filter Grounding
Ferrite Bead Attenuation
Isolation Transformers for DC and AC Power CM/DM Filtering

6. GROUNDING/BONDING
Primary Grounding Configurations
Safety Earthing/Grounding vs EME Coupling
Grounding Myths vs Reality
Electrical Shock Avoidance (UL, NEC Req's)
Lightning Protection Systems
Filter Grounding
Bond Zo of Round/Flat Conductors & Planes
Contact Surfaces
MIL-B-5087 and MIL-STD-1310 Bond Classes
MIL-STD-464A Bonding Criteria
Class B & C Bonding
Type I, II, III, & IV Bond Straps
Practical Solutions (Appendix A)
Impedance Reduction

7. HULL/EQUIPMENT SHIELDING
Near Field (EF and HF)
Far Field/Plane Wave
Metal Barrier Performance
External/Internal Reflection & Absorption
Graphical representation
Cavity Amplification - Below Decks
Shielding Performance of Typical Metals
Absorption and Reflection equations
Shielding Effectiveness vs Frequency
Low Frequency Magnetic Shielding
Principal Seam Design Configurations
High Performance Enclosure Seams
Mechanical/Electrical Considerations
RF Gasket Mechanical/Electrical Considerations

Qualitative Shielding Effectiveness
Shielding Compromises
Aperture Integrity
Calculation of Aperture SE
Combination of Multiple Apertures
Window and Vent panels
SE of Screen Meshes
Conductive Glass
Waveguide-Below-Cutoff Effect
Honeycomb Air Filters
Component Penetrations (Fuses, Switches, Meters, Displays, etc.)
Hull/Cable Penetrations

8. ELECTRO-GALVANIC COMPATIBILITY
Corrosion a Major Ship board and Coastal Problem
Corrosion Induced EMC Failures
Conditions Necessary for Corrosion
Galvanic Potentials and Coupling
Shielded Enclosure Seams
Oxidation/Reduction Reaction
Preventing Corrosion
Protection Requirements
Faying Surface Preparation
Interstitial Conductive/Non-Conductive Faying Materials (A5.2/5.3)

9. TRANSMITTER/RECEIVER EMI PROBLEMS
Transmitters and Receivers Simplified
Receiver Bandwidth Considerations (5.5)
Purpose of Receiver Pre-selector
Co-Channel EMI
Adjacent Channel EMI
Tx Fundamental to Rx Fundamental
Tx Noise to Rx Fundamental
Tx Fundamental to Rx Spurs
Tx Spurs to Rx Spurs
Receiver Overload/Desensitization
Receiver Overload/Desensitization
Transmitter & Receiver Intermodulation
Hull Intermodulation/Interference
Nonmetallic Structural and Equipment Components

10. ANTENNA EMC CHARACTERISTICS
Antenna and Transmission Line Fundamentals
Frequency vs Wavelength
Structural Resonance
Basic Passive Antenna Types (Monopole, Yagi, LP, Horn, Dish)
Active Adaptive Antenna Arrays
Gain and Bandwidths
Polarization
Electric Field (EF) vs Power & Gain
Antenna Patterns, Main Beam & Side Lobes
Cosite Antenna to Antenna Coupling
Antenna Placement/Separation
Isolation by Directional Antennas, Antenna Shrouds, Blanking, Adaptive Antennas
Superstructure and Other Blockages
Reflections From Conducting Surfaces, Cylinders, and Corners
RF Absorber Materials
Ship to Ship Isolation by F A S T.

11. DETERMINING/TROUBLE SHOOTING SYSTEMS EMC PROBLEMS
Systems Problems
Systems Test Approach
Data Collection
Writing ElectroMagnetic Scenarios
Solving Problems

12. LIGHTNING/ELECTROSTATIC DISCHARGE (ESD)
Electron Mobility and Charge Creation
Mechanism of ESD/Lightning
ESD/Lightning Coupling into Electronic Systems
Radial and Linear Current Flow
Direct & Indirect Discharge
Circuit/Cabling Hardening
ESD/Lightning Shielding /Protection

13. PERSONNEL SAFETY - ELECTRIC SHOCK & RADHAZ
Electric Shock Overview
Electrical Shock Statistics
Resistors / Insulators / Conductors
Shipboard Electrical Power Systems
Comparison of Grounded/Ungrounded Power Distribution
RF Filter Leakage Currents
Shock, Burns & Other Injuries
Preventing Electrical Hazards
Grounding & Double Insulation
Circuit Protection devices
Flow Chart for Safe Work Practices
LockOuts/Tags

14. PERSONNEL SAFETY - RADHAZ
Hazards of Electromagnetic Radiation to Personnel (HERP)
DOD 6055.11-1995 RF/MW RADHAZ Exposure Guidelines
SAR based
DOD Controlled/Uncontrolled RF Limits
Induced and Contact Current Limits
Electrostatic Charges Cranes/Helicopters
RF Burns
Relaxation for Partial-Body Exposures
Warning Signs
Preventive Measures

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