What it is, what it does, What it is, what it does, how to protect your stationhow to protect your station

Rick Blasco, NX6RRick Blasco, NX6R

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What is EMP?What is EMP?

• ElectroMagnetic Pulse caused by:ElectroMagnetic Pulse caused by:– LightningLightning– Geomagnetic stormGeomagnetic storm– Power line transientPower line transient– Thermonuclear detonationThermonuclear detonation– E-bombE-bomb

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What is EMP?What is EMP?

• ElectroMagnetic Pulse caused by:ElectroMagnetic Pulse caused by:– LightningLightning– Geomagnetic stormGeomagnetic storm– Power line transientPower line transient– Thermonuclear detonationThermonuclear detonation– E-bombE-bomb

LightningLightning

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LightningLightning

• Weak “tracer” pulse cloud to ground, Weak “tracer” pulse cloud to ground, followed by strong “return” pulses ground followed by strong “return” pulses ground to cloud to cloud

• 3-4 pulses or “strokes” per “flash” or 3-4 pulses or “strokes” per “flash” or “strike”“strike”

• Peak current 3 kA to 175 kA (18 kA typ)Peak current 3 kA to 175 kA (18 kA typ)• Spectrum falls off more rapidly than Spectrum falls off more rapidly than

thermonuclearthermonuclearcrossover 1-10 MHzcrossover 1-10 MHz

NX6RNX6RDennis BodsonDennis Bodson [3] [3] and Ron Block KB2UYT and Ron Block KB2UYT [4] [4] and and in in QSTQST

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Thunderstorm days per yearThunderstorm days per year

Ron Block KB2UYT in Ron Block KB2UYT in QST QST [4][4]

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Strikes per year vs. tower heightStrikes per year vs. tower height

Ron Block KB2UYT in Ron Block KB2UYT in QST QST [4][4]

ThermonuclearThermonuclear

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ThermonuclearThermonuclear

• Compton effect: gamma rays interact with Compton effect: gamma rays interact with atmosphere to produce EMPatmosphere to produce EMP

• Can cover large geographic areaCan cover large geographic area

• Less likely to occur than other sourcesLess likely to occur than other sources

• EMP probably “least of your worries”EMP probably “least of your worries”

• Three “strokes” of EMPThree “strokes” of EMP

NX6RNX6RDennis Bodson W4PWF in Dennis Bodson W4PWF in QST QST [3][3]

E1 and E2 pulse propagationE1 and E2 pulse propagation

NX6RNX6RDr. John Foster, et al. Dr. John Foster, et al. 1994 EMP Threat Assessment Report1994 EMP Threat Assessment Report [5][5]

E3 pulse propagationE3 pulse propagation

NX6RNX6RDr. John Foster, et al. Dr. John Foster, et al. 1994 EMP Threat Assessment Report1994 EMP Threat Assessment Report [5][5]

EMP propagation vs altitudeEMP propagation vs altitude

NX6RNX6RDennis Bodson W4PWF in Dennis Bodson W4PWF in QST QST [3][3]

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E-bombE-bomb

"Gort! Klaatu barada nikto!" "Gort! Klaatu barada nikto!"

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E-bombE-bomb

Carlo Kopp in Carlo Kopp in Air & Space Power JournalAir & Space Power Journal [1] [1]

• Localized EMP effectLocalized EMP effect

• Cheap to make ($1000-$2000)Cheap to make ($1000-$2000)

• Commonly available materialsCommonly available materials

• Well-known technology (since 1940s)Well-known technology (since 1940s)

• Multiple delivery methodsMultiple delivery methods

• Peak current of large device stronger than Peak current of large device stronger than lightning strokelightning stroke

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““Ideal” terrorist weaponIdeal” terrorist weapon• Highly disruptive if properly placedHighly disruptive if properly placed

• Minimum “collateral” damageMinimum “collateral” damage

• Cheap to makeCheap to make• Commonly available materialsCommonly available materials

no need to smuggle into countryno need to smuggle into country

• Conventional C-4 plastic explosive Conventional C-4 plastic explosive impossible to detect from a distanceimpossible to detect from a distance

• Can be fitted in a van and driven to target Can be fitted in a van and driven to target sitesite

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Coaxial Flux Compression Generator (FCG)Coaxial Flux Compression Generator (FCG)

Carlo Kopp in Carlo Kopp in Air & Space Power JournalAir & Space Power Journal [1] [1]

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Virtual Cathode Oscillator (VIRCATOR)Virtual Cathode Oscillator (VIRCATOR)

Carlo Kopp in Carlo Kopp in Air & Space Power JournalAir & Space Power Journal [1] [1]

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Characteristics of an EMP pulseCharacteristics of an EMP pulse

• Extremely high energyExtremely high energy• Very short durationVery short duration

→ → Energy in RF spectrumEnergy in RF spectrum

Pulse shapesPulse shapes

Carlo Kopp in Carlo Kopp in Air & Space Power JournalAir & Space Power Journal 1996 1996 [1][1]

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Approximate Spectrum of EMPApproximate Spectrum of EMP

Dennis Bodson W4PWF in Dennis Bodson W4PWF in QSTQST[3][3]

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What it doesWhat it does

• Presents high voltage and high current to:Presents high voltage and high current to:– AntennasAntennas– Transmission linesTransmission lines– Rotor cablesRotor cables– Power cablesPower cables– Microphone and other external cablesMicrophone and other external cables– Internal equipment wiringInternal equipment wiring– PC board tracesPC board traces– Semiconductor junctions Semiconductor junctions

(diodes, transistors, ICs)(diodes, transistors, ICs)– Vacuum tubesVacuum tubes– Passive components Passive components

(capacitors, resistors, inductors, etc.)(capacitors, resistors, inductors, etc.)

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Will it move?Will it move?

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Will all this stuff work?Will all this stuff work?

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Will you have acceWill you have acce$$$$??

““We should have left it buried in the backyard.”We should have left it buried in the backyard.”

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If it can arc, smoke, or melt …If it can arc, smoke, or melt …

IT CAN FRY!IT CAN FRY!

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How it does itHow it does it

• ConductionConduction– Antenna systemAntenna system– Power linesPower lines– Ground connectionGround connection

• InductionInduction– Cables and wires act as antennasCables and wires act as antennas– Coils, chokes, and transformers act as voltage Coils, chokes, and transformers act as voltage

generatorsgenerators

Larry Scheff W4QEJ in February 2008 Larry Scheff W4QEJ in February 2008 QST QST [2][2]

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Ohm’s Law (DC)Ohm’s Law (DC)

ERI

PIE

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Ohm’s Law (RF - simplified)Ohm’s Law (RF - simplified)

Irf

Vrf 2πfcVrf

Irf 2πfL

22ππ = 6.28 = 6.2831853073185307

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Ohm’s Law (RF - simplified)Ohm’s Law (RF - simplified)

Prf

cPrf

LIrf

2

Vrf

2

2 2

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Protection (hardening) techniquesProtection (hardening) techniques

• Disconnect external cablesDisconnect external cables

• ““Stout”Stout” grounding grounding

• Transient suppressorsTransient suppressors

• Energy-tolerant componentsEnergy-tolerant components

• Faraday cage / shieldingFaraday cage / shielding

Ron Block KB2UYTRon Block KB2UYT in in QSTQST [4] [4]

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““Stout” GroundingStout” Grounding

Ron Block KB2UYTRon Block KB2UYT in in QSTQST [4] [4]

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““Stout” GroundingStout” Grounding

• Common “bulkhead” ground pointCommon “bulkhead” ground point“single-point ground panel”“single-point ground panel”

• Suppressors Suppressors externalexternal to building to buildingkeep the strokes outside!keep the strokes outside!

• Multiple ground rods interconnected with #6 Multiple ground rods interconnected with #6 or larger wire per National Electrical Codeor larger wire per National Electrical Code

Ron Block KB2UYTRon Block KB2UYT in in QSTQST [4] [4]

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Lightning suppressorsLightning suppressors

Ron Block KB2UYTRon Block KB2UYT in in QSTQST [4] [4]

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Modified Faraday CageModified Faraday Cage

• Steel file cabinetSteel file cabinet• Add steel plate to close bottomAdd steel plate to close bottom• Single connection to groundSingle connection to ground• Energy flows around the faraday “shell” to groundEnergy flows around the faraday “shell” to ground• Good shielding below 10 MHzGood shielding below 10 MHz• Add shielding gaskets around drawers for Add shielding gaskets around drawers for

protection to VHF/UHFprotection to VHF/UHF• Store spare equipment, microphones, antennas, Store spare equipment, microphones, antennas,

coax, and cables for use after “attack”coax, and cables for use after “attack”

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Other measuresOther measures

• Reduce Reduce inductanceinductance of ground connections of ground connectionslarge diameter wire or copper flashing 1”-3” widelarge diameter wire or copper flashing 1”-3” wide

• Multiple length parallel wires to ground rodsMultiple length parallel wires to ground rodsavoid odd avoid odd λλ/4 multiples throughout spectrum/4 multiples throughout spectrum

• Shorten length between power line suppressors Shorten length between power line suppressors and equipmentand equipment

• Coil cablesCoil cableskeep ends separatedkeep ends separated

• Optical fibreOptical fibre• Optical storage (CDs and DVDs)Optical storage (CDs and DVDs)

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Ohm’s Law (RF - simplified)Ohm’s Law (RF - simplified)

Irf

Vrf 2πfcVrf

Irf 2πfL

22ππ = 6.28 = 6.2831853073185307

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Other measuresOther measures

• Reduce Reduce inductanceinductance of ground connections of ground connectionslarge diameter wire or copper flashing 1”-3” widelarge diameter wire or copper flashing 1”-3” wide

• Multiple length parallel wires to ground rodsMultiple length parallel wires to ground rodsavoid odd avoid odd λλ/4 multiples throughout spectrum/4 multiples throughout spectrum

• Shorten length between power line suppressors Shorten length between power line suppressors and equipmentand equipment

• Coil cablesCoil cableskeep ends separatedkeep ends separated

• Optical fibreOptical fibre• Optical storage (CDs and DVDs)Optical storage (CDs and DVDs)

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ReferencesReferences1.1. Kopp, Carlo “The Electromagnetic Bomb - a Weapon of Electrical Mass Destruction”, Kopp, Carlo “The Electromagnetic Bomb - a Weapon of Electrical Mass Destruction”, Air Air

& Space Power Journal& Space Power Journal 1996 1996

2.2. Scheff, Larry W4QEJ “Lightning: Understand It or Suffer the Consequences” Scheff, Larry W4QEJ “Lightning: Understand It or Suffer the Consequences” QSTQST Parts 1-2: February, March 2008 Parts 1-2: February, March 2008

3.3. Bodson, Dennis W4PWF “Electromagnetic Pulse and the Radio Amateur” Bodson, Dennis W4PWF “Electromagnetic Pulse and the Radio Amateur” QST QST Parts 1-4: August, September, October, November 1986Parts 1-4: August, September, October, November 1986condensed from “Electromagnetic Pulse/Transient Threat Testing of Protection Devices for Amateur/Military Affiliate condensed from “Electromagnetic Pulse/Transient Threat Testing of Protection Devices for Amateur/Military Affiliate Radio System Equipment” National Communication Systems Report Radio System Equipment” National Communication Systems Report NCS TIB 85-10NCS TIB 85-10

4.4. Block, Ron KB2UYT “Lightning Protection for the Amateur Station” Block, Ron KB2UYT “Lightning Protection for the Amateur Station” QSTQST Parts 1-3: June, July, August 2002Parts 1-3: June, July, August 2002

5.5. Foster, Gjelde, Graham, Hermann, Kluepfel, Lawson, Soper, Wood, and Woodard Foster, Gjelde, Graham, Hermann, Kluepfel, Lawson, Soper, Wood, and Woodard “Report of the Commission to Assess the Threat to the United States from “Report of the Commission to Assess the Threat to the United States from Electromagnetic Pulse (EMP) Attack” 2004, commissioned by Public Law 106-398, Title Electromagnetic Pulse (EMP) Attack” 2004, commissioned by Public Law 106-398, Title XIV, XIV, §1402§1402

6.6. Tracy, Mike KC1SX “Lightning Protection” Tracy, Mike KC1SX “Lightning Protection” QSTQST Lab Notes Lab NotesParts 1-2: October, December 1994Parts 1-2: October, December 1994