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DEPARTMENT OF THE ARMY EP 1110-3-2
U.S. Army Corps of Engineers
CEMP-ET Washington, DC 20314-1000
Pamphlet
No. 1110-3-2 31 December 1990
Engineering and Design
ELECTROMAGNETIC PULSE (EMP) AND TEMPEST PROTECTION FOR FACILITIES
1. Purpose. This pamphlet provides unclassified engineering and design
information about protecting fixed ground facilities against the effects of an
electromagnetic pulse (EMP) produced by a nuclear explosion. It also provides
unclassified engineering and design information about satisfying TEMPEST
requirements.
2. Applicability. This pamphlet applies to all HQUSACE/OCE elements, major
subordinate commands, districts, laboratories, and field operating activities
(FOA) having military construction and design responsibilities.
3. Discussion. The enclosed material constitutes a general reference work on
the specialized subject of electromagnetic pulse (EMP) and TEMPEST protection.
It was assembled over several years by our Construction Engineering Research
Laboratory. The designer who is interested in the theory behind the design
will find this material useful. The designer will also find information on
aspects of the subject not normally part of the design effort.
FOR THE COMMANDER:
Encl
[Signature]
ROBERT L. HERNDON
Colonel, Corps of Engineers
Chief of Staff
------------------------------------------------------------------------------
ELECTROMAGNETIC PULSE (EMP) AND TEMPEST PROTECTION FOR FACILITIES
TABLE OF CONTENTS
Paragraph Page
CHAPTER 1. INTRODUCTION
Scope..............................................1-1 1-1
Application........................................1-2 1-1
References.........................................1-3 1-1
Background.........................................1-4 1-2
Pamphlet organization..............................1-5 1-2
CHAPTER 2. EMP ENVIRONMENT
Outline............................................2-1 2-1
HEMP: detailed discussion..........................2-2 2-2
Other EMP environments.............................2-3 2-5
Environment-to-facility coupling...................2-4 2-9
Equipment susceptibility...........................2-5 2-16
Cited references...................................2-6 2-19
Uncited references.................................2-7 2-20
CHAPTER 3. EMP HARDENING CONCEPTS FOR FACILITIES
Outline............................................3-1 3-1
Discussion of general concepts.....................3-2 3-1
Description of HEMP hardening concepts.............3-3 3-4
Cited reference....................................3-4 3-10
Uncited references.................................3-5 3-10
CHAPTER 4. SYSTEM ENGINEERING REQUIREMENTS
Outline............................................4-1 4-1
Standards and specifications.......................4-2 4-1
Electromagnetic integration........................4-3 4-2
HEMP and lightning protection integration..........4-4 4-2
HEMP/TEMPEST and electromagnetic integration.......4-5 4-4
Environmental requirements.........................4-6 4-5
Cited references...................................4-7 4-6
CHAPTER 5. FACILITY DESIGN [not digitized here]
Outline............................................5-1 5-1
Theoretical approach to shielding..................5-2 5-5
Shield design methodology..........................5-3 5-6
Solid shields......................................5-4 5-10
Shielded enclosures................................5-5 5-20
Mesh and perforated type shields...................5-6 5-21
Layered shields....................................5-7 5-27
Reinforcement steel (rebar)........................5-8 5-27
Earth cover electromagnetic wave attenuation.......5-9 5-30
Shield joints and seams............................5-10 5-31
Internal cable and connectors......................5-11 5-35
Conduit and conduit connections....................5-12 5-38
Terminal protection for electrical penetrations....5-13 5-43
Apertures..........................................5-14 5-52
Utility penetrations...............................5-15 5-55
Bonding............................................5-16 5-55
Grounding..........................................5-17 5-61
Cited references...................................5-18 5-64
Uncited references.................................5-19 5-67
CHAPTER 6. EMP AND TEMPEST TESTING REQUIREMENTS [not digitized here]
Outline............................................6-1 6-1
Introduction.......................................6-2 6-3
Testing requirements versus facility mission.......6-3 6-4
Susceptibility testing.............................6-4 6-4
Quality assurance testing..........................6-5 6-6
Acceptance testing.................................6-6 6-7
Hardness assessment and validation testing.........6-7 6-9
Life-cycle testing.................................6-8 6-10
Test methodology...................................6-9 6-11
Free-field illuminators............................6-10 6-12
Current injection testing..........................6-11 6-17
Shielding effectiveness testing....................6-12 6-27
Bonding impedance measurements.....................6-13 6-34
Cited references...................................6-14 6-35
Uncited references.................................6-15 6-36
CHAPTER 7. PROTECTION MAINTENANCE AND SURVEILLANCE [not digitized here]
Outline............................................7-1 7-1
Introduction.......................................7-2 7-2
Facility life cycle environment....................7-3 7-2
Hardening shielding elements.......................7-4 7-3
Impact of hardness maintenance on facility
design............................................7-5 7-4
Hardness maintenance program structure.............7-6 7-7
Hardness surveillance (HS) activities..............7-7 7-10
Cited references...................................7-8 7-13
CHAPTER 8. EMP AND TEMPEST RISKS
Outline............................................8-1 8-1
Introduction.......................................8-2 8-2
EMP environment--overview..........................8-3 8-2
Comparison of HEMP and lightning...................8-4 8-5
TEMPEST risks......................................8-5 8-5
Cited references...................................8-6 8-10
CHAPTER 9. EMP AND TEMPEST PROTECTION CONCEPTS
Outline............................................9-1 9-1
Introduction.......................................9-2 9-1
TEMPEST requirement in relation to HEMP............9-3 9-4
Generic facility hardening.........................9-4 9-5
CHAPTER 10. SYSTEMS INTEGRATION [not digitized here]
Outline............................................10-1 10-1
Introduction.......................................10-2 10-1
Protection system integration......................10-3 10-2
Internal systems...................................10-4 10-2
Environmental systems..............................10-5 10-2
General integration................................10-6 10-3
CHAPTER 11. DESIGN AND SPECIFICATION PROCESS [not digitized here]
Outline............................................11-1 11-1
Introduction.......................................11-2 11-2
Design approach....................................11-3 11-2
Typical design process.............................11-4 11-3
General shield design problem areas................11-5 11-23
CHAPTER 12. TEMPEST-SHIELDED FACILITIES
Outline............................................12-1 12-1
Introduction.......................................12-2 12-2
Design criteria for 50-decibel facilities..........12-3 12-2
RF shield design for 50-decibel facilities.........12-4 12-3
Penetration protection devices.....................12-5 12-10
Cited references...................................12-6 12-li
Uncited reference..................................12-7 12-11
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LIST OF FIGURES
Figure 2-1. The Compton process.....................................2-25
2-2. (Not used.)
2-3. Variations in high-altitude EMP peak electric
field strength as a function of direction and
distance from surface zero.............................2-27
2-4. HEMP waveform...........................................2-28
2-5. Qualitative time domain example of HEMP.................2-29
2-6. Qualitative frequency domain example of HEMP............2-30
2-7. Surface-burst EMP showing source region and
radiated region........................................2-31
2-8. Overview of surface-burst EMP...........................2-32
2-9. Radiated vertical electric field--large
surface burst..........................................2-33
2-10. Air-burst EMP--source region............................2-34
2-11. Air-burst EMP--radiated region..........................2-35
2-12. Three modes of penetration and coupling into
shielded enclosures....................................2-36
2-13. Magnetic shielding effectiveness of an
enclosure with solid walls and an
enclosure with rebar...................................2-37
2-14. Magnetic shielding effectiveness of an
ideal enclosure and an enclosure with
openings...............................................2-38
2-15. Ground-based facilities--unintentional
antennas...............................................2-39
2-16. EMP coupling to facility penetrations...................2-40
2-17. Two mechanisms by which EMP couples to
conductors.............................................2-41
2-18. Equivalent circuit for a small electric
dipole.................................................2-42
2-19. Equivalent circuit for a small loop (magnetic
dipole)................................................2-43
2-20. Modeling example--microwave tower and
equivalent fat cylindrical monopole....................2-44
2-21. Shielded cables and transfer impedance..................2-45
2-22. Transmission line coupling..............................2-46
2-23. Aerial conductors: effect of conductor length...........2-47
2-24. Buried conductors: effect of burial depth...............2-48
2-25. Ringing.................................................2-49
2-26. Typical internal signal cable distribution
diagram................................................2-50
2-27. Intrasite cables........................................2-51
2-28. EMP system interaction..................................2-52
2-29. Energy level ranges, in joules, that damage
various components.....................................2-53
2-30. Examples of transient upset.............................2-54
2-31. Range of pulse power damage constants for
representative transistors.............................2-55
2-32. Range of pulse power damage constants for
representative semiconductors..........................2-56
3-1. Building examples showing three concepts for
critical equipment protection..........................3-11
3-2. Zonal shielding concept.................................3-12
3-3. Underground facility with four zones....................3-13
3-4. Zonal shielding concept with steel-reinforced
concrete as shield 1....................................3-14
3-5. Shielded enclosure: cable entry vault...................3-15
3-6. Optical fiber shield penetration........................3-16
4-1. Processes and currents occurring in a flash
to ground..............................................4-12
4-2. EMP and lightning comparison............................4-13
4-3. Sample power line surge voltage as a function
of distance from stroke to line........................4-14
4-4. Typical spectrum of lightning radiated E-field..........4-15
4-5. Average radiated and static fields for
lightning..............................................4-16
5-1. Transmission line model of shielding....................5-97
5-2. Correction factor in correction term for
internal reflections...................................5-98
5-3. Shield absorption loss nomograph........................5-99
5-4. Nomograph for determining magnetic field
reflection loss........................................5-100
5-5. Nomograph for determining electric field
reflection loss........................................5-101
5-6. Nomograph for determining plane wave
reflection loss........................................5-102
5-7. Chart for computing K for magnetic field
secondary reflection loss..............................5-103
5-8. Chart for computing secondary losses for
magnetic fields........................................5-104
5-9. Absorption loss for steel and copper shields at
30 hertz to 10,000 megahertz...........................5-105
5-10. Absorption loss for copper and iron, in
decibels per mil.......................................5-106
5-11. Shielding effectiveness in electric, magnetic,
and plane wave fields of copper shields
(7 mils thick) for signal sources 165 feet
from the shield........................................5-107
5-12. Shielding effectiveness in electric, magnetic,
and plane wave fields of steel shield (1 mil
thick) for signal sources 165 feet from
the shield.............................................5-108
5-13. Shielding effectiveness in electric, magnetic,
and plane wave fields of steel shield
(50 mils thick) for signal sources 165 feet
from the shield........................................5-109
5-14. Minimum shielding effectiveness of low-carbon
steel walls............................................5-110
5-15. Performance characteristics of typical commercial
shielded enclosures....................................5-111
5-16. Mean shielding effectiveness for all test points
for the June 1980 test.................................5-112
5-17. (not used.)
5-18. Aperture shielding......................................5-114
5-19. (Not used.)
5-20. (Not used.)
5-21. (Not used.)
5-22. Attenuation--rectangular waveguide......................5-119
5-23. Attenuation--circular waveguide.........................5-120
5-24. Air impedance of perforated metal and honeycomb.........5-121
5-25. Air impedance of copper and nickel mesh.................5-122
5-26. (Not used.)
5-27. Center area attenuation of 5-meter-high,
single-course reinforcing steel room...................5-124
5-28. Center area attenuation of 10-meter-high,
single-course reinforcing steel room...................5-125
5-29. Correction curves for various rebar diameters
and spacings using single-course rebar
construction...........................................5-126
5-30. Shielding degradation versus distance from wall.........5-127
5-31. Shielding effectiveness of reinforcement steel..........5-128
5-32. Reinforcement steel welding practice....................5-129
5-33. Schematic presentation--reinforcement steel
shield.................................................5-130
5-34. Weld joints for sheet steel shields.....................5-131
5-35. Bolted joints for metallic shields......................5-132
5-36. Shielding effectiveness for bolted joints...............5-133
5-37. Influence of screw spacing on shielding
effectiveness..........................................5-134
5-38. Gasket deflection limits (in inches)....................5-135
5-39. Typical mounting techniques for RF gaskets..............5-136
5-40. Improper gasket application.............................5-137
5-41. EMI shielded door seam (mesh gasket)....................5-138
5-42. EMI shielded door seam ("oval" spiral gasket)...........5-139
5-43. EMI shielded door seam (fingerstock)....................5-140
5-44. Shielding effectiveness and transfer impedance..........5-141
5-45. A braided-shield coaxial cable..........................5-142
5-46. Cable shielding effectiveness with number
of braid layers........................................5-143
5-47. Lossy conductor construction............................5-144
5-48. Attenuation of HEMP interference propagating
on lossy-wrapped conductors............................5-145
5-49. Induction loop area for twisted pair cables.............5-146
5-50. Experiments with shielded twisted pair cabling..........5-147
5-51. Construction of some popular coaxial connectors.........5-148
5-52. Contact resistance of conductive coatings
on aluminum............................................5-149
5-53. Shielding effectiveness of connectors with
various finishes.......................................5-150
5-54. Effect of tightening torque on shielding
effectiveness during vibration.........................5-151
5-55. Effect of added spring fingers on shielding
effectiveness..........................................5-152
5-56. Effect of adding shielding gaskets on connector
shielding effectiveness................................5-153
5-57. Normalized transfer impedance for solid
cylindrical shields....................................5-154
5-58. Magnitude of the transfer impedance of rigid
steel conduit..........................................5-155
5-59. Flaw impedance (ZF) of typical coupling.................5-156
5-60. Diffusion signal for 1-inch galvanized steel
conduit showing sense wire voltage.....................5-157
5-61. Flaw impedance (ZF) of 0.038-millimeter
(0.015-inch) wall flex-joint with and without
copper strap...........................................5-158
5-62. Flaw impedance (ZF) of 0.76-millimeter
(0.03-inch) wall flex-joint with and without
copper strap..........................................5-159
5-63. Experimental HEMP hardened union........................5-160
5-64. Type C conduit body.....................................5-161
5-65. Machined conduit body cover for HEMP hardening..........5-162
5-66. "Wrap-around" junction box cover........................5-163
5-67. (Not used.)
5-68. (Not used.)
5-69. (Not used.)
5-70. (Not used.)
5-71. The four basic filter classes...........................5-168
5-72. Ferrite bead on wire and ferrite bead equiv-
alent circuit..........................................5-169
5-73. Filter pin connector design.............................5-170
5-74. Shunt and series transformer wiring
configuration..........................................5-171
5-75. Typical shielded door closures..........................5-172
5-76. Emergency escape hatch configuration....................5-174
5-77. Typical welded screen installation over a
ventilation aperture...................................5-175
5-78. Typical clamped screen installation over a
ventilation aperture...................................5-176
5-79. Honeycomb material for shielding air vents..............5-177
5-80. Waveguide attenuation as a function of
waveguide dimensions...................................5-178
5-81. Air vent HEMP protection design.........................5-179
5-82. Conduit or metal pipe penetration design................5-180
5-83. HEMP protection for waveguide entry.....................5-181
5-84. Plastic pipe termination practices......................5-182
5-85. Theoretical attenuation of the TE11 mode
for a 1.5-inch (3.8-centimeter) internal
diameter pipe with distilled water for
various loss tangents..................................5-184
5-86. Cutoff frequency versus relative dielectric
constant for various pipe diameters....................5-185
5-87. Effects of poor bonding on the performance
of a power line filter.................................5-186
5-88. Bolted bond between flat bars...........................5-187
5-89. Bracket installation (bolt).............................5-188
5-90. Bonding of connector to mounting surface................5-189
5-91. Bolting of bonding jumpers to flat surface..............5-190
5-92. Bonding to rigid conduit................................5-191
5-93. Equivalent circuit for bonding strap....................5-192
5-94. True equivalent circuit of a bonded system..............5-193
5-95. Techniques for protecting bonds between
dissimilar metals......................................5-194
5-96. Zonal grounding.........................................5-195
5-97. Minimum earth electrode system configuration
for rectangular--shaped facility.......................5-196
5-98. Electrode configuration for irregular-shaped
facility...............................................5-197
5-99. Current path on zonal boundaries........................5-198
5-100. Typical hybrid ground configuration.....................5-199
5-101. Typical ground configurations for HEMP
protection.............................................5-200
6-1. Bounded wave simulators.................................6-43
6-2. Pulsed radiated wave simulators.........................6-44
6-3. Continuous wave testing--CW test configuration..........6-46
6-4. Direct current injection testing........................6-47
6-5. Inductive current injection testing.....................6-48
6-6. Direct drive test for penetrating conductor
(conceptual sketch)....................................6-49
6-7. Transfer impedance/admittance test setup................6-50
6-8. Alternative demonstration and test methods..............6-51
6-9. Response characteristic measurement.....................6-52
6-10. Standard circuit for measuring S parameters.............6-53
6-11. Response measurement....................................6-54
6-12. HEMP stress test........................................6-55
6-13. TPD power attenuation test..............................6-56
6-14. Alternative power attenuation test using
simulated subsystem impedance..........................6-57
6-15. Static breakdown voltage measurement....................6-58
6-16. Small-loop-to-small-loop test setup.....................6-59
6-17. Proposed measurement points for small-loop
test...................................................6-60
6-18. Test setup for Helmholtz coil field
generation.............................................6-61
6-19. Parallel strip line technique...........................6-62
6-20. Attenuation measurement--high-impedance
electric field.........................................6-63
6-21. Attenuation test for plane waves (wave
impedance = 377 ohms)..................................6-64
6-22. Parallel plate line.....................................6-65
6-23. Sweep frequency bonding measurement system..............6-66
7 1. Effect of hardening approach on subsystem
design.................................................7-15
7-2. Interaction of HM/HS/TSM program elements...............7-16
7-3. Configuration management process........................7-17
7-4. Example of maintenance procedures.......................7-18
8-1. Near-surface and exoatmospheric blasts..................8-13
8-2. Time waveform for the free-field HEMP
electric field.........................................8-14
8-3. HEMP ground coverage for bursts of various
heights above the United States........................8-15
8-4. Reasonable worst-case TEMPEST shielding
attenuation requirement................................8-16
8-5. Fifty-decibel (nominal) TEMPEST pipe or air
duct penetration design................................8-17
11-1. Required electromagnetic attenuation....................11-32
11-2. Checklist for HEMP drawings.............................11-33
12-1. Efficient TEMPEST facility floor plan...................12-12
12-2. Typical clamped modular shield room joints..............12-13
12-3. Typical penetration panel installation in a
modular shielded enclosure.............................12-14
12-4. Steel plate floor shield design.........................12-15
12-5. Floor plate shield construction technique...............12-16
12-6. Foil wall shield construction technique.................12-17
12-7. Foil/foil seam..........................................12-18
12-8. Sheet metal/foil seam...................................12-19
12-9. Foil shield pipe penetration design.....................12-20
------------------------------------------------------------------------------
LIST OF TABLES
Table 2-1. Important features of EMP environments....................2-21
2-2. EMP waveform summary......................................2-22
2-3. Response thresholds.......................................2-23
2-4. Typical EMP transients and equipment
thresholds--EMP threat level.............................2-24
4-1. HEMP/TEMPEST-related standards and
specifications...........................................4-8
4-2. Peak magnetic field values for close lightning
strokes..................................................4-11
5-1. Coefficients for magnetic field reflection loss...........5-69
5-2. Absorption loss of metals at 150 kilohertz................5-70
5-3. Absorption loss of solid copper, aluminum, and
iron shields at 60 hertz to 10,000 megahertz.............5-71
5-4. Reflection loss...........................................5-72
5-5. Shield effectiveness in magnetic field (wave
impedance much smaller than 377 ohms) of solid
copper, aluminum, and iron shields for signal
source 12 inches from the shield at 150 kilo-
hertz to 100 megahertz...................................5-73
5-6. Shielding effectiveness in plane wave field
(wave impedance equal to 377 ohms) of solid
copper and iron shields for signal sources
greater than 2 inches from the shield at 150
kilohertz to 100 megahertz...............................5-74
5-7. Shielding effectiveness in electric field (wave
impedance much greater than 377 ohms) of solid
copper, aluminum, and iron shields for signal
source 12 inches from the shield at 0.15
megahertz to 100 megahertz...............................5-75
5-8. Re-reflection (B) factors in electric, magnetic,
and plane wave fields of solid copper and iron
shields..................................................5-76
5-9. Shielding effectiveness in electric, magnetic,
and plane wave fields of copper shield (7 mils
thick) for signal source 165 feet from the
shield at 30 hertz to 10 gigahertz.......................5-78
5-10. Shielding effectiveness in electric, magnetic,
and plane wave fields of steel shield (1 mil
thick) for signal source 165 feet from the
shield at 30 hertz to 10 gigahertz.......................5-79
5-11. Shielding effectiveness in electric, magnetic,
and plane wave fields of steel shield (50 mils
thick) for signal source 165 feet from the shield
at 30 hertz to 10 gigahertz..............................5-80
5-12. Sample calculations of shielding effectiveness
for solid metal shield...................................5-81
5-13. Peak voltage induced on 10-meter radius loop
inside 10-meter radius spherical shield by the
high-altitude EMP (by diffusion through the
walls only)..............................................5-83
5-14. Effectiveness of nonsolid shielding materials
against low-impedance and plane waves....................5-84
5-15. Effectiveness of nonsolid shielding materials
against high-impedance waves.............................5-85
5-16. Comparison of measured and calculated values of
shielding effectiveness for No. 22, 15-mil
copper screens...........................................5-86
5-17. (Not used.)
5-18. Application factors for welded wire fabric................5-88
5-19. Typical values of conductivity for soils
and rock.................................................5-89
5-20. Skin depth (d) and absorption loss (A) for
nonmetal materials.......................................5-90
5-21. Electromotive series......................................5-91
5-22. Characteristics of conductive gasketing
materials................................................5-92
5-23. (Not used.)
5-24. Comparison of protection devices..........................5-94
5-25. Galvanic series for selected metals.......................5-95
5-26. Relative advantages and disadvantages of the
principal types of earth electrodes......................5-96
6-1. Test applicability........................................6-37
6-2. Summary of existing bounded-wave simulators...............6-38
6-3. Summary of radiating wave simulators......................6-39
6-4. Scaling relationships.....................................6-40
6-5. Summary of quality assurance test methods.................6-41
6-6. Comparison of shielding effectiveness test
methods..................................................6-42
7-1. Qualitative tradeoff study results........................7-14
8-1. Comparison of HEMP with lightning-induced
stresses on long overhead power lines....................8-12
11-1. Power line surge arrester criteria........................11-26
11-2. Power line filter criteria................................11-27
11-3. Signal and control line protection: coaxial
penetrations.............................................11-28
11-4. Twisted shielded pair criteria............................11-29
11-5. Terminal protection device................................11-30
11-6. Shielding effectiveness test points.......................11-31
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CHAPTER 1
INTRODUCTION
1-1. Scope.
a. Focus. The focus in this pamphlet is on electromagnetic pulse (EMP)
produced by nuclear explosions at high altitudes (high-altitude EMP, or HEMP).
Herein, the terms EMP and HEMP are used synonymously. In many cases
facilities are not targeted for other nuclear effects and a HEMP event is the
worst-case scenario for ground-based facilities. Therefore, many protective
measures described herein will also protect against some other electromagnetic
environments.
b. Subjects not covered. Specific protection methods for other types of
EMP, such as source-region EMP and surface-burst EMP are not covered. In
addition, this pamphlet does not cover protection against other effects of
nuclear explosions (for example, blast overpressure and thermal/nuclear
radiation).
c. TEMPEST problem. The TEMPEST problem is nearly the inverse of the HEMP
event. TEMPEST is the unclassified name for the studies and investigation of
compromising emanations. Equipment within the facility can be the source of
electromagnetic waves and stray currents/voltages with characteristics which
are related to the information content of signals being processed. If these
unintentional emissions are intercepted and studied, the analyst can
reconstruct the original data and could gain access to national security
information A proper TEMPEST design, however, will preclude the presence of
analyzable signals in uncontrolled areas.
d. Common treatment. Thus, HEMP and TEMPEST protective measures must each
control electromagnetic energy, the former protecting system equipment from
externally generated signals and the latter containing emissions from internal
sources. The functional similarities imply that a common treatment can be
employed for the two purposes.
1-2. Application. Information in this pamphlet is applicable to engineers
responsible for the design, construction, and maintenance of mission-critical
facilities, such as those supporting the command, control, communications and
intelligence network. The information is relevant to new construction as well
as to additions, upgrades, and retrofits to existing facilities.
1-3. References. This pamphlet is intended to stand alone and, as such, no
additional references should be required to understand the material herein.
However, only a small sample of the material published on HEMP and TEMPEST can
be highlighted here. Because different facilities will have differing
requirements for protection, supplementary sources are listed at the end of
most chapters to assist the engineer in designing protection on a case-by-
case basis.
1-4. Background.
a. Reliance on electronic technology. Military facilities are becoming
increasingly reliant on automated systems that take advantage of modern
electrical and electronic technology. Facilities are equipped with state-of
the-art computerized systems for expeditious, reliable, and cost-effective
operations. However, the electromagnetic (EM) properties of many electronic
components can make entire systems susceptible to upset or permanent damage
due to the environmental effects of EMP. Systems are also susceptible to the
compromise of security information by the unintentional intelligence-bearing
emanations of electromagnetic signals. Thus, with the benefits of automation
has come an increased vulnerability.
b. Early planning. Techniques to protect a facility are usually selected
during the early design phase. If it is anticipated that a facility may
someday acquire equipment that must be protected, early planning can avoid
costly retrofitting later. The decision to harden will be based on the
interaction of mission criticality, electromagnetic environment, security
requirements, and costs.
c. Far-reaching effects. HEMP is dangerous because this event has far-
reaching effects at distances where other nuclear environments are either
nonexistent or inconsequential and because of its high level of broad spectral
energy. However, the spectrum included under HEMP does not cover all EM
environments. For example, the characteristic pulse risetime and possible
conducted current waveforms for lightning differ from those for HEMP; thus,
hardening against HEMP does not necessarily protect against lightning.
d. Evolving technology. It is important to note that this field is
relatively new and that technical expertise is still evolving. Therefore, it
is the designer's responsibility to stay current with new developments to
assure the most cost-effective reliable configuration for vital military fixed
facilities.
1-5. Pamphlet organization. At the beginning of each subsequent chapter,
there is an outline. The purpose of the outline is to provide more detail on
the chapter's content than is ordinarily appropriate in a table of contents.
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[End Chapter 1]