Radar and Stealth Technology

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Radar and Stealth Technology

• By Blake Sharin

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Outline

• Background
• Radar
• How radar works
• Echo and Doppler Shift
• Understanding Radar
• Stealth Technology
• History
• How it works
• Future

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Who uses Radar Systems?

• Radar is used everyday
• Air Traffic Control
• Police
• NASA
• Military
• Meteorologists

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Echo and Doppler Shift

• Echo occurs because some of the sound waves in
  your shout reflect off of a surface (either the
  water at the bottom of the well or the canyon
  wall on the far side) and travel back to your
  ears.
• The length of time between the moment you shout
  and the moment that you hear the echo is
  determined by the distance between you and the
  surface that creates the echo.

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Echo and Doppler Shift (Contd.)

• Doppler shift occurs when sound is generated by,
  or reflected off of, a moving object.
• Doppler shift in the extreme creates sonic booms.
• Let's say there is a car coming toward you at 60
  miles per hour (mph) and its horn is blaring. You
  will hear the horn playing one "note" as the car
  approaches, but when the car passes you the sound
  of the horn will suddenly shift to a lower note.
  It's the same horn making the same sound the
  whole time. The change you hear is caused by
  Doppler shift.

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Echo and Doppler Shift (Contd.)

• Combine Echo and Doppler shift
• If you send out a loud sound toward a car moving
  toward you, some of the sound waves will bounce
  off the car (an Echo).
• Because the car is moving toward you, the sound
  waves will be compressed. Therefore, the sound of
  the echo will have a higher pitch than the
  original sound you sent.
• If you measure the pitch of the echo, you can
  determine how fast the car is going.

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Understanding Radar

• The echo of a sound can be used to determine how
  far away something is.
• The Doppler shift of the echo can determine how
  fast something is going.
• Sound radar creates what is known as sonar.
• Boats and Submarines
• You could use the same principles with sound in
  the air, but sound in the air has a couple of
  problems

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What are the problems? Solutions?

• Sound doesn't travel very far
• About a mile at the most.
• Almost everyone can hear sounds, so a "sound
  radar" would definitely disturb the neighbors.
• Because the echo of the sound would be very
  faint, it is likely that it would be hard to
  detect.
• Radar therefore uses radio waves instead of
  sound.
• Radio waves travel far, are invisible to humans
  and are easy to detect even when they are faint.

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How are Airplanes Measured?

• The idea is for the radar antenna to send out a
  burst of radio energy, which is then reflected
  back by any object it happens to encounter.
• The radar antenna measures the time it takes for
  the reflection to arrive, and with that
  information can tell how far away the object is.
• The metal body of an airplane is very good at
  reflecting radar signals, and this makes it easy
  to find and track airplanes with radar equipment.

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Stealth Technology

• The goal of stealth technology is to make an
  airplane invisible to radar. There are two
  different ways to create invisibility
• The airplane can be shaped so that any radar
  signals it reflects are reflected away from the
  radar equipment.
• The airplane can be covered in materials that
  absorb radar signals.
• Most conventional aircraft have a rounded shape.
  This shape makes them aerodynamic, but it also
  creates a very efficient radar reflector.
• The round shape means that no matter where the
  radar signal hits the plane, some of the signal
  gets reflected back

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Stealth Technology (Contd.)

• A stealth aircraft, on the other hand, is made up
  of completely flat surfaces and very sharp edges.
• When a radar signal hits a stealth plane, the
  signal reflects away at an angle
• Surfaces on a stealth aircraft can be treated so
  they absorb radar energy.
• The overall result is that a stealth aircraft
  like an F-117A can have the radar signature of a
  small bird rather than an airplane.

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Stealth Technology (Contd.)

• The only exception is when the plane banks.
• There will often be a moment when one of the
  panels of the plane will perfectly reflect a
  burst of radar energy back to the antenna.
• Is it ironic that stealth planes resemble UFO
  Drawings and sightings?

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Future of Stealth Technology

• In the future, stealth technology will not only
  be incorporated in fighters and bombers but also
  in ships, helicopters, tanks and transport
  planes.

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References

• http//www.lowobservables.com/
• http//people.howstuffworks.com/