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8/6/2019 Fundamentos de energía
http://slidepdf.com/reader/full/fundamentos-de-energia 1/34
Naval Weapons Systems Naval Weapons Systems
Energy FundamentalsEnergy Fundamentals
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Learning Objectives Learning Objectives
Comprehend the basic application of Comprehend the basic application of electronic systems and electromagneticelectronic systems and electromagneticwave theory to applications in radars,wave theory to applications in radars,communications, and radio navigationcommunications, and radio navigationsystems.systems.
Comprehend radar and radio waveComprehend radar and radio waveparameters.parameters.
8/6/2019 Fundamentos de energía
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Learning Objectives Learning Objectives
Know and be able to apply radar andKnow and be able to apply radar andradio wave theory (Maxwell·s Theory;radio wave theory (Maxwell·s Theory;wl,f ,v relationship)wl,f ,v relationship)
Comprehend the basic operation of aComprehend the basic operation of asimple radar/ radio systemsimple radar/ radio system
Comprehend the concepts of time andComprehend the concepts of time anddistance as they affect wave phase angledistance as they affect wave phase angleand interference.and interference.
8/6/2019 Fundamentos de energía
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Learning Objectives Learning Objectives
Know basic electromagnetic interferenceKnow basic electromagnetic interferencefactors in ship and weapons designfactors in ship and weapons design
Know electromagnetic wave propagationKnow electromagnetic wave propagation(reflection, refraction, diffraction, and(reflection, refraction, diffraction, andducting)ducting)
Define: ground plane, free space, reDefine: ground plane, free space, re--radiation, sky wave, space wave, groundradiation, sky wave, space wave, groundwaves, and troposphere waves.waves, and troposphere waves.
8/6/2019 Fundamentos de energía
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Energy Fundamentals Energy Fundamentals
One important weapon systemOne important weapon systemrequirements is the ability to detectrequirements is the ability to detect
targets.targets.Detection accomplished throughDetection accomplished through
exploiting the electromagneticexploiting the electromagnetic
spectrumspectrumElectromagnetic energy comes in manyElectromagnetic energy comes in manyforms: RADAR, Micro /Radio waves,forms: RADAR, Micro /Radio waves,IR, Light, Sound...IR, Light, Sound...
8/6/2019 Fundamentos de energía
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Energy Fundamentals Energy Fundamentals
OverviewOverviewRADARRADAR
Electromagnetic (EElectromagnetic (E--M)WaveM)Wave
CharacteristicsCharacteristics
Maxwell·s TheoryMaxwell·s Theory
PolarizationPolarization
InterferenceInterference
Propagation of EPropagation of E--M wavesM waves
Transmission Range factorsTransmission Range factors
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Energy Fundamentals Energy Fundamentals
RADAR RADAR RARAdio dio DDetectionetection AAndnd RRanging anging
Radar is anRadar is an electromagnetic waveelectromagnetic wave that acts like anythat acts like anyother electromagnetic wave (i.e.other electromagnetic wave (i.e. -- radio , light, etc.)radio , light, etc.)
Characteristics of a radio wave assuming aCharacteristics of a radio wave assuming afrequency of 2 Hertz:frequency of 2 Hertz:
Cycle
Amplitude
1 second
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T raveling WaveT raveling Wave
CharacteristicsCharacteristicsFrequencyFrequencyMeasuredMeasured
in Hertz (Hz)in Hertz (Hz)
(Cycles/sec)(Cycles/sec)
Wavelength = Speed of Light / Wavelength = Speed of Light / FrequencyFrequency
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T raveling WaveT raveling Wave
CharacteristicsCharacteristicsPeriodPeriodThe time requiredThe time required
for a full cyclefor a full cycle
Inverse of FrequencyInverse of Frequency
T=1/ fT=1/ f
T
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T raveling WaveT raveling Wave
CharacteristicsCharacteristics Wavelength Wavelength
The distanceThe distance
between 2 identicalbetween 2 identical
points on adjacentpoints on adjacent
waveswaves
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T raveling WaveT raveling Wave
CharacteristicsCharacteristicsCoherencyCoherency
A wave that is pureA wave that is pure
Sinusoid and aSinusoid and a
singular frequencysingular frequency
AdvantagesAdvantages::--Doppler shift canDoppler shift can
be measured.be measured.
--Better signal to noise ratio.Better signal to noise ratio.
CoherentCoherent
No
nNo
n--Co
herentCo
herent
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T raveling WaveT raveling Wave
CharacteristicsCharacteristicsVelocityVelocity
The speed of lightThe speed of light
AmplitudeAmplitude
Distance from theDistance from the
baseline to the crest of the wavebaseline to the crest of the wave
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M axwell·s T heory M axwell·s T heory
An accelerating electric field willAn accelerating electric field willgenerate a timegenerate a time--varying magneticvarying magnetic
field.field.
A timeA time--varying magnetic field willvarying magnetic field will
generate a timegenerate a time--varying electric field.varying electric field.
...and so on...and so on...and so on......and so on...and so on...and so on...
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Generation of Electromagnetic RadiationGeneration of Electromagnetic Radiation
+
-
+
-
-
+
a b c d
= Alternating Current
Source
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Formation of Electric and M agnetic Formation of Electric and M agnetic
Fields around an Antenna Fields around an Antenna
e- e- e-
E-line
Mag field
Electric field _|_ Magnetic Field _|_ Direction ofPropagation.
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End of Part 1 End of Part 1
Questions ?Questions ?
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Energy Energy
Fundamentals FundamentalsPart IIPart II
PolarizationPolarization
InterferenceInterference
Wave Pro
pagatio
n Wave Pro
pagatio
n Wave Types Wave Types
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What is Polarization?What is Polarization?
TheThe directiondirection of polarization of of polarization of an antenna is defined as thean antenna is defined as the
electric field vectorelectric field vector..
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I nterference I nterference
Electromagnetic wave interference canElectromagnetic wave interference canbe bothbe both
²² ConstructiveConstructiveNet field strength > Individual fieldNet field strength > Individual field
²² DestructiveDestructive
Net field strength < Individual fieldNet field strength < Individual field
Interference varies with phase angleInterference varies with phase angle
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Constructive I nterferenceConstructive I nterference
Constructive InterferenceConstructive Interference
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Constructive I nterferenceConstructive I nterference
Destructive InterferenceDestructive Interference
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Propagation Paths of E Propagation Paths of E--M M
WavesWavesReflectionReflection
RefractionRefractionDiffractionDiffraction
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... Reflection...... Reflection...
Incident WaveReflected Wave
Surface type plays a role in the amount of Surface type plays a role in the amount of energy reflectedenergy reflected
Angle of incidence = Angle of reflectedAngle of incidence = Angle of reflectedwave.wave.
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... Refraction...... Refraction...
-- Incident wave passes through two Incident wave passes through two transparent media in which thetransparent media in which thevelocity of light differs...velocity of light differs...
-- Incident wave divides into a Incident wave divides into areflected wave and a refracted wave.reflected wave and a refracted wave.
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... Diffraction...... Diffraction...
island
notdetected
detected
...plane waves traveling in a straight...plane waves traveling in a straightpath bend around a boundary orpath bend around a boundary oro
bstructio
n.o
bstructio
n.
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Wave PropagationWave Propagation --relationship between distancerelationship between distance
and frequencyand frequency
G
round WavesG
round WavesSky WavesSky Waves
Space WavesSpace Waves
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Ground Wave...Ground Wave...
Very low frequenciesVery low frequencies
Vertical polarizationVertical polarization
Waves travel along earth·s surface. Waves travel along earth·s surface.
55--10Khz10Khz
Very l
ong wavelengths
Very l
ong wavelengths -- unsuitableunsuitablefor ships & aircraft, except commsfor ships & aircraft, except comms
ShoreShore--based installations (HFbased installations (HF--DF)DF)
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Sky Wave...Sky Wave...
EE--M energy refracts back towards theM energy refracts back towards theearth·s surface in upper ionosphereearth·s surface in upper ionospherelayer.layer.
EE--M energy then reflects back towardM energy then reflects back towardupper layer again.upper layer again.
Frequencies used up to 550 KHzFrequencies used up to 550 KHz
effectivelyeffectively Wavelengths still too long for Wavelengths still too long for
anything but comms by aircraft andanything but comms by aircraft and
ships.ships.
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Space Wave...Space Wave...
Above 30 MHz, ionosphere will notAbove 30 MHz, ionosphere will notrefract Erefract E--M waves back toward earth.M waves back toward earth.
Energy tends to travel in straight line.Energy tends to travel in straight line.
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Ducting ... Ducting ...
Phenomenon which enhances thePhenomenon which enhances therange of electromagnetic waves.range of electromagnetic waves.
Usually occurs w/temperatureUsually occurs w/temperatureinversion.inversion.
Cold AirCold Air
Warm Air Warm Air
Cold AirCold Air
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T ransmission LossesT ransmission Losses
Spreading: Energy per unitSpreading: Energy per unit
area pro
po
rtio
nal to
1/R.area pro
po
rtio
nal to
1/R.Absorption: Molecules of Absorption: Molecules of
medium absorb some of themedium absorb some of the
energy as it passes through.energy as it passes through.
22
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SummarySummary
RADARRADAR
Electromagnetic (EElectromagnetic (E--M)WaveM)WaveCharacteristicsCharacteristics
Maxwell·s TheoryMaxwell·s Theory
PolarizationPolarization
InterferenceInterference
Propagation of EPropagation of E--M wavesM waves
Transmission Range factorsTransmission Range factors
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Questions ?Questions ?