2. CONTENTSCONTENTS
• What isWhat is RADARRADAR??
• Evolution ofEvolution of RADARRADAR..
• Principle of working ofPrinciple of working of RADARRADAR..
• Working of aWorking of a RADARRADAR systems.systems.
• RADARRADAR signal processing.signal processing.
• Antenna designing inAntenna designing in RADARRADAR..
• RADARRADAR modulators.modulators.
• Fields of application ofFields of application of RADARRADAR..
• BestBest RADARRADAR system in the world.system in the world.
3. EVOLUTION OF RADAREVOLUTION OF RADAR
• In 1886, a German physicistIn 1886, a German physicist Heinrich HertzHeinrich Hertz analyzedanalyzed
thatthat Radio Waves could be reflected from the solidRadio Waves could be reflected from the solid
objects.objects.
• In 1895,In 1895, Alexander PopovAlexander Popov wrote that this Phenomenonwrote that this Phenomenon
might be used for detecting objects.might be used for detecting objects.
• In 1904,the German inventorIn 1904,the German inventor Christian HulsmeyerChristian Hulsmeyer waswas
the first to use radio waves to detect “the first to use radio waves to detect “the presence ofthe presence of
distant metallic objectsdistant metallic objects”.”.
4. ? RADAR? RADAR
• RADARRADAR is an object detection system whichis an object detection system which
uses radio waves to determine theuses radio waves to determine the
range,altitude, direction and speed of objects.range,altitude, direction and speed of objects.
• The termThe term RADARRADAR was coined in 1940 by Unitedwas coined in 1940 by United
States Navy for “States Navy for “RARAdiodio DDetectionetection AAndnd RRanging”.anging”.
• There are basically two types of radars-There are basically two types of radars-
1.1.CountinousCountinous wave radar, 2.wave radar, 2.PulsePulse radar.radar.
8. PRINCIPLES OF WORKINGPRINCIPLES OF WORKING
• A radar system has a Transmitter that emits radio wavesA radar system has a Transmitter that emits radio waves
calledcalled radar signalradar signal inin predetermined directions.predetermined directions.
• When these signals come into contact with an objectWhen these signals come into contact with an object
they are usuallythey are usually reflectedreflected in many directions.in many directions.
• There is a slight equivalent change in the frequency ofThere is a slight equivalent change in the frequency of
radar waves caused byradar waves caused by Doppler effect.Doppler effect.
• The receiver receives the reflected signals that can beThe receiver receives the reflected signals that can be
strengthened by using electronic amplifiers andstrengthened by using electronic amplifiers and signalsignal
processing methods .processing methods .
9.
10. DOPPLER EFFECTDOPPLER EFFECT
• Frequency shift is caused by motion that changes theFrequency shift is caused by motion that changes the
number ofnumber of wavelengths between the reflector and thewavelengths between the reflector and the
radarradar..
11. RADAR SIGNALRADAR SIGNAL
PROCESSINGPROCESSING
• 1. Distance Measurement1. Distance Measurement
• For theFor the pulse radarpulse radar the round trip-time is used tothe round trip-time is used to
detect the distance.detect the distance.
• The distance inThe distance in continuous wave radarcontinuous wave radar isis
measured by the product of one half of the trip-measured by the product of one half of the trip-
time and the speed of signal.time and the speed of signal.
12. RADAR SIGNALRADAR SIGNAL
PROCESSINGPROCESSING
• 2.Speed2.Speed MeasurementMeasurement
• In a radar, the variation between the phase ofIn a radar, the variation between the phase of
successive returns, gives the distance, the target hassuccessive returns, gives the distance, the target has
moved between pulses.moved between pulses.
RF genera-
tore
IF genera-
tore
mixer
BPF
circulator
detector
IF
amplifier
detector
LPF
Frequency counter display
Antenna
13. Why signal processing ?Why signal processing ?
• Signal processing is employed in radar systems toSignal processing is employed in radar systems to
reduce the radar interference effect.reduce the radar interference effect.
• Constant alarm rate and digital terrain objectConstant alarm rate and digital terrain object processingprocessing
are also used in clutter environments.are also used in clutter environments.
14. ANTENNA DESIGNING IN RADARANTENNA DESIGNING IN RADAR
• Radio signals broadcast from a single antennaRadio signals broadcast from a single antenna
will spread out in all directions, and likewise awill spread out in all directions, and likewise a
single antenna will receive signals equally fromsingle antenna will receive signals equally from
all directions.all directions.
• Early systems tended to use omni-directionalEarly systems tended to use omni-directional
broadcast antenna, with directional receiverbroadcast antenna, with directional receiver
antennas which were pointed in variousantennas which were pointed in various
directions.directions.
15. ANTENNA DESIGNING IN RADARANTENNA DESIGNING IN RADAR
• Parabolic antenna is usedParabolic antenna is used
in the radar system.in the radar system.
• Parabolic antennaParabolic antenna
produce a narrow beamproduce a narrow beam
in one dimension and ain one dimension and a
relatively wide beam inrelatively wide beam in
the other dimension.the other dimension.
16. ANTENNA DESIGNING IN RADARANTENNA DESIGNING IN RADAR
PARAB-OLIC
ANTENNA
PHASED ARRAY
ANTENNA
DIPOLE ANTENNA
SLOTTED
WAVEGUIDE
ANTENNA
Cassegrain
antenna
17. RADIATION PATTERN OFRADIATION PATTERN OF
ANTENNASANTENNAS
PARABOLIC
ANTENNA
PHASED
ARRAY
ANTENNA
CASSEGRAIN
ANTENNA
SLOTTED
WAVEGUID
E ANTENNA
18. RADAR MODULATORRADAR MODULATOR
• Modulators act to provide the waveform of the RF-pulse.Modulators act to provide the waveform of the RF-pulse.
• The Hydrogen thyratron modulator is the most commonThe Hydrogen thyratron modulator is the most common
radar modulatorradar modulator
• The shape and duration of the pulse are determined byThe shape and duration of the pulse are determined by
the electrical characteristics of the pulse-formingthe electrical characteristics of the pulse-forming networknetwork
High voltage
power supply
Charging diode
Charging coil
Pulse forming network
c1
R1
Thyratron Pulse transformer
19. THE THYRATRONTHE THYRATRON
• A typical thyratron is a gas-filled tube for radarA typical thyratron is a gas-filled tube for radar
modulator.modulator.
• The high-vacuum tube modulator is to act as a switch toThe high-vacuum tube modulator is to act as a switch to
turn a pulse ON and OFF at the transmitter in responseturn a pulse ON and OFF at the transmitter in response
to a control signal.to a control signal.
GRID
Anode
Filament
Cathode
Gas filling
20. FIELDS OF APPLICATIONFIELDS OF APPLICATION
• MILITARYMILITARY
• REMOTE SENSINGREMOTE SENSING
• AIR TRAFFIC CONTROLAIR TRAFFIC CONTROL
• HIGHWAY SECURITYHIGHWAY SECURITY
• NAVIGATIONNAVIGATION
• SHIP SECURITYSHIP SECURITY
• SPACE (SATTELITS )SPACE (SATTELITS )
21. RADAR IN DAY TO DAY LIFERADAR IN DAY TO DAY LIFE
• MICROWAVE IMPULSE RADAR USES TO DETONATMICROWAVE IMPULSE RADAR USES TO DETONAT
SMALL BOMBS.SMALL BOMBS.
• BY ATTACHING A EXTENDER RADAR CAN BE USEDBY ATTACHING A EXTENDER RADAR CAN BE USED
TO SEARCH FOR TRAPPED PEOPLE.TO SEARCH FOR TRAPPED PEOPLE.
• TUNNEL WALL INSPECTION.TUNNEL WALL INSPECTION.
• MINE INSPECTION.MINE INSPECTION.
• LOCATING UNDERGROUND PIPES.LOCATING UNDERGROUND PIPES.
• LOCATING GRAVES.LOCATING GRAVES.
22. ADVANTAGES OF RADARADVANTAGES OF RADAR
• RADAR provide superior penetration capability throughRADAR provide superior penetration capability through
any type of weather condition, and can be used in theany type of weather condition, and can be used in the
day or night timeday or night time!!
• Radar uses radio wave that does not require aRadar uses radio wave that does not require a
medium, so can be used in space and airmedium, so can be used in space and air!!
• Radar can be long range and the wave propagate atRadar can be long range and the wave propagate at
the speed of light rather then sound (like with sonar)the speed of light rather then sound (like with sonar)!!
• Very flexible - can be used in a number of waysVery flexible - can be used in a number of ways !!
• Stationary modeStationary mode!!
• Moving modeMoving mode!!
• Beam spread can incorporate many targetsBeam spread can incorporate many targets !!
• Can often select fastest target or best reflectionCan often select fastest target or best reflection !!
• Still very reliable and advancedStill very reliable and advanced!!
23. DISADVANTAGES OF RADARDISADVANTAGES OF RADAR
• Time - Radar can take up to 2 seconds to lock on !Time - Radar can take up to 2 seconds to lock on !
• Radar has wide beam spread (50 ft diameter over 200 ftRadar has wide beam spread (50 ft diameter over 200 ft
range)!range)!
• More interference sourcesMore interference sources. .
Make copies for distribution. 1. Transmit/Receive Antennas. Since must operate simultaneously, must be located separately so receiving antenna doesn’t pick up transmitted signal. 2. Oscillator or Power Amplifier. Sends out signal to transmit antenna. Also sends sample signal to Mixer. (used as a reference) 3. Mixer. a. A weak sample of the transmitted RF energy is combined with the received echo signal. b. The two signal will differ because of the Doppler shift. c. The output of the mixer is a function of the difference in frequencies. 4. Amplifier. Increases strength of signal before sending it to the indicator. 5. Discriminator. a. Selects desired frequency bands for Doppler shifts, eliminates impossible signals. b. The unit will only allow certain frequency bands so won’t process stray signals. 6. Indicator. Displays data. Displays velocity or the component directly inbound or directly outbound. Range is not measured . 7. Filters. Used to reduce noise, used in amp to reduce sea return, land clutter, and other non-desirable targets.
