This presentation is on how a radar works, echo and Doppler shifts. what stealth technology is about and how it works.

1. RADAR AND STEALTH
TECHNOLOGY

2. Outline
 Background
 Radar
 How radar works
 Echo and Doppler Shift
 Understanding Radar
 Stealth Technology
 History
 How it works
 Future

3. Who uses Radar Systems?
 Radar is used
everyday
 Air Traffic Control
 Police
 NASA
 Military
 Meteorologists

4. 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.

5. 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.

6. 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.

7. 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

8. 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.

9. 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.

10. 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

11. 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.

12. 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?

13. 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.

14. References
 http://www.lowobservables.com/
 http://people.howstuffworks.com/

15. THANK YOU