AGENDA – EMC FOR SPACE SYSTEMS, FACILITIES, AND EQUIPMENT

The following is a quote from Spacecraft EMC P R O B L E M S, www.evaluationengineering.com, April/May 2007. "There are many wise old sayings within the aerospace industry. Some of them are humorous, some of them may annoy your friends, and some may cause you to loose your attaboy. This one may be pushing the limit on my attaboy, but it is one of those sage aerospace tenets that conveys the differences between scientists and engineers. It goes like this: When the rocket gets off its pad and the payload successfully reaches its destination the scientists have had another break-through . . . but let that rocket blow up on the pad and the engineers have screwed up again."

An electromagnetic compatibility (EMC) problem induced launch failure is generally not as spectacular as having a solid fuel rocket blow up on the pad and scatter its remains over a 1/2 square mile area, but EMC has certainly accounted for a large number of very expensive mission losses. Some of these launch vehicle (LV) and spacecraft (SC) combinations can run around $3,000,000,000 and more. Yes! There is supposed to be 9 zeros! Consequently an EMC engineer working in the aerospace industry doesn’t want to be branded as one of those engineers that screwed up again. Plus you don't get a second chance! In the LV/SC world it has to be done right the first time, though in the case of the Hubble Telescope NASA did get to do some on-orbit repairs. A rarity in the LV/SC world. The picture at the left is the International Space Station.

This course covers the primary space systems EMC problems. It does not contain ITAR/EAR/DOD restricted information. The course is based entirely on published open source materials.


EMC FOR SPACE SYSTEMS, FACILITIES, AND EQUIPMENT

UNDERSTANDING EMC AND EMC REQUIREMENTS
  • Course Overview
  • EMC Terms and Definitions
  • EMI Sources, Victims, and Paths
  • Transients - Lightning, ESD, EMP
  • FAST Analysis
  • SPACE SYSTEMS EMI/EMC REQUIREMENTS
  • A Brief Overview of LV/SC requirements Documents
  • MIL-STD-461C/F TEST REQUIREMENTS AND PROCEDURES
  • Determining the required tests based on platform and user Selected MIL-STD-461 test limits and test procedures
  • Conducted emission tests
  • Conducted susceptibility tests
  • Radiated electric field (EF) emission
  • Radiated electric field susceptibility tests
  • Miscellaneous tests from MIL-STD-461C
  • COMMERCIAL OFF THE SHELF EQUIPMENT
  • EMC Limitations of Commercial Off The Shelf Equipment (COTS)
  • COTS Pro and Con
  • CI/NDI Overvoew from MIL-STD-237C
  • Differences Between Commercial and Military Standards
  • Risks of Using Commercial Test Data
  • EMC SYSTEMS DESIGN/PROBLEM CONSIDERATIONS
  • The 3 Most Important EMC Design Rules
  • Key EMC Design Facilitators
  • Circuit Response to EMI
  • CONDUCTED VS RADIATED COUPLING
  • Simplified Loop Radiation
  • Simplified Loop Pickup
  • Wavelength vs Frequency
  • Amplitude vs Time vs Frequency
  • Spectrum Density vs Pulse Shape
  • EMC CIRCUIT DESIGN EMPHASIS
  • Design Approaches
  • Radiation Loops
  • Making Loop Areas Smaller
  • Basic PCB Layout
  • CABLING EMC DESIGN & INSTALLATION
  • Coupling by DM, CM, and Antenna Modes
  • Differential Mode Loop Area
  • Reduce DM Loops
  • DM Radiation Pattern
  • HF from Two Parallel Wires
  • Twist Attenuation
  • Use Shielded Cable
  • Reducing DM Coupling
  • Reducing Field to Cable DM Coupling
  • Common Mode (CM) Loop Area
  • Shielding to minimize DM and CM
  • CABLE TO CABLE CROSSTALK
  • Cable Design
  • Cable Segregation/Isolation
  • Electric and Magnetic Crosstalk
  • Crosstalk Waveform Distortion
  • DOD-W-83575A Wire Harness
  • EED Wire/Cable Requirements
  • FILTERS & ISOLATION TRANSFORMERS FOR CONTROL OF CE/CS
  • Filters
  • Inter and Intra System Filters
  • Inductor-Capacitor Resonance
  • Filter Attenuation vs Elements
  • Prototype Butterworth LP Filter
  • Filter Attenuation vs Source Impedance
  • Isolation Transformers
  • Performance of Ordinary Isolation Transformer
  • Double-Shielded Isolation Transformer
  • Typical attenuation Shielded-Isolation Transformers
  • GROUNDING/BONDING
  • Grounding and Bonding Rationale
  • Single and Multipoint grounding
  • Earth Grounding
  • Lightning Protection for Power & Signal Cables
  • Cable and Connector Grounding
  • Box and System-Level Grounding
  • Wire Grid and Plane Impedance
  • Bonding Impedance vs Material
  • Practical Solutions
  • SHIELDING FUNDAMENTALS
  • EF & HF from Small Antenna
  • Wave Impedance vs Distance
  • Shielding Equations
  • Low Frequency HF Shielding
  • Sources of Discontinuities
  • Cable/Connector EMC Areas
  • Shield Cable Connections
  • Connector Shielding
  • ENCLOSURE AND PAYLOAD FAIRING SHIELDING
  • Scattering in Thin Materials
  • Slot Aperture
  • Circular Apertures
  • Mechanical/Electrical Considerations
  • Aperture Integrity
  • Waveguide-Below-Cutoff Effect
  • Cable Penetrations
  • Cable Shielding
  • Effects of Enclosure Size
  • Modeling the Payload Fairing as a Shield
  • Cavity Amplification
  • Absorber Materials
  • SEAM DESIGN AND CONSTRUCTION
  • Butt Seams
  • Compressive Seams
  • SE vs Closure Pressure
  • Shear Seams
  • Four Popular RF Gasket Types
  • Qualitative Shielding Effectiveness
  • Shielding Degradation from Finish
  • ELECTRO-GALVANIC COMPATIBILITY
  • Corrosion Induced EMC Failures
  • Galvanic Couples
  • Oxidation/Reduction Reaction
  • Preventing Corrosion
  • Launch Site Protection Requirement
  • MIL-STD-1250 -- Gold Reference
  • LIGHTNING/ELECTROSTATIC DISCHARGE (ESD)
  • Electron Mobility and Charge Creation
  • Mechanism of ESD and Lightning
  • ESD/Lightning Coupling into Electronic Systems
  • Radial and Linear Current Flow
  • Direct & Indirect Discharge
  • ESD Shielding: Conductive vs Plastic Enclosures
  • Facilities/Lightning Protection
  • Launch Weather Constraints
  • Circuit/Cabling Hardening
  • ESD Test and Evaluation
  • MULTIPACTION & SPACE CHARGING
  • Ionization Breakdown
  • RF Voltage Thresholds
  • Radiation effects on electronic systems
  • Single Event Effects (SEU/SEL/SEB)
  • Photoelectric Emission
  • Dielectric Charging from High energy Particles
  • EMC/COSITE & OUT OF BAND INTERFERENCE
  • Transmitter/Receiver EMC Problems
  • Receiver Bandwidth Considerations
  • Co-Channel EMI
  • Adjacent Channel EMI
  • Problems With Hand Held Transmitters
  • Receiver Overload/Desensitization
  • Transmitter Inhibits
  • What is Out of band interference
  • Field strength, power & antenna gain
  • Intermodulation products
  • Out of band Interference Control
  • Rusty Bolt Intermodulation/Interference

  • Antenna EMC Characteristics
  • Antenna Fundamentals
  • Gain and Bandwidths
  • Polarization
  • Electric Field (EF) vs Power & Gain
  • RADHAZ
  • Cosite Antenna to Antenna Coupling
  • Antenna Placement/Separation
  • Re-Rad Antennas
  • Isolation by Directional Antennas, Antenna Shrouds/Hats, Blanking and Adaptive Antennas
  • Blockages from Superstructure, Launch Platform, Gantry, and Other Objects
  • Reflections from Conducting Surfaces, Cylinders, and Corners
  • RF Absorber Material
  • Isolation by F A S T
  • RF LINK MARGIN
  • Simplified Link Model
  • Influencing Factors
  • Atmospheric Attenuation
  • Signal Propagation

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