gives more information abt its types and applications......

1. PRESENTED BY:
M.A.ARAVINDLAL
R.NANDHA KUMAR
P.S.PRASAANTH
P.RAJU
S.SARAVANAN
M.MESHAKPRABHAKARAN
S.BALAJI

2. 1. Introduction to radar
2. History
3. Components & range
4. atmospheric effects
5. Radar classification.
6. Advantages&disadvantages
7. conclusion

3. Antenna
Transmitted
Pulse
Radar observables:
• Target range
• Target angles (azimuth & elevation)
• Target size (radar cross section)
• Target speed (Doppler)
• Target features (imaging)
Target
Cross
Section
Propagation
Reflected
Pulse
(“echo”)

4.  Bats use a basic form of radar
 They send sound waves that reflect off of an
object just as electric radar systems do

5.  The first form of radar created by humans
was the telemobiloscope
 It was mainly used to detect ships to avoid
collisions

6.  Radar was kept fairly secret during world
war II
 Following the war, it was published that the
United States used radar to measure the
distance to the moon
 It was later discovered that Hungary had
done this two years earlier than the U.S.

7. Radar Frequencies

8.  The components of a radar system.
 1. Transmitter
 2. Antenna
 3. Receiver
 4. Display unit
 5. Power supply
 6. Duplexer( improved radar).

9.  Distance from the
radar
Measured from time
delay between
transmitted pulse and
returned signal
received

10.  Remember, in general v=d/t and d=vt
 The range is just a distance
 Since radio waves travel at the speed of
light (v = c = 300,000 km/sec )
range = c•time/2
 Why divided by 2?

11.  The “2” is because the measured time is for
a round trip to and from the target. To
determine the range, you only want the time
to the object, so you take half!

12. Target
• Target range =
ct
2
where c = speed of light
t = round trip time

14. Radar beams can be attenuated, reflected and
bent by the environment
• Atmospheric attenuation
• Reflection off of earth’s
surface
• Over-the-horizon
diffraction
• Atmospheric refraction

15.  that the Doppler effect is the change in
frequency that occurs when a source and a
target are in relative motion.
 The Doppler affect can be used in a CW radar
in order to determine velocity.

17.  Fd = 2Vr
λ
Fd = doppler shift
Vr = relative velocity of target with respect to
radar.

18. Motion Away:
Echo Frequency Decreases
Motion Towards:
Echo Frequency Increases

19.  Pulse Transmission
Continuous Wave

21. Employs continual
RADAR transmission
 Separate transmit and
receive antennas
Relies on the
“DOPPLER SHIFT”

22.  Continuous wave (CW) radars typically
determine target velocity, and can achieve
considerable ranges without the high peak
power. These radars are typically simpler,
more compact and less costly.

23. CW RF
Oscillator
Discriminator AMP Mixer
Indicator
OUT
IN
Transmitter Antenna
Antenna

24.  An unmodulated CW radar is incapable of
detecting range, as there is no reference
point in the transmitted or returned signal
for measuring elapsed time.
By frequency modulating the CW signal,
differences between the transmitted and
received frequencies can be used to
estimate range.

25. Pulse Echo
 Single Antenna
Comparitively low
SNR
Susceptible To
Jamming
Physical Range
Determined By PW.
Continuous Wave
Requires 2 Antennae
 High SNR
More Difficult to Jam
But Easily Deceived
Amp can be tuned to
look for expected
frequencies

26.  Penetration Capability
 Uses electromagnetic wave so it require no
medium
 Less susceptible to weather conditions
 Flexible – can be used in number of ways
 Beam spread can incorporate many targets
 Reliable

27.  Time factor
Wide beam spread
 Larger targets can saturate receiver
 Possibility of falsify readings
 Interference sources

28.  Airplanes use radar to avoid collisions and to
coordinate landings
 Operators visually watch the radar outputs
and relay the information to pilots

29.  Police officers use radar to detect people
who drive over the speed limit
 Their radar units are compact for easy
portability and fast, accurate use

30.  Ground mapping radar is often used in
construction settings
 They drag the unit across the ground to
determine if there are any objects or
unstable soil where they plan on building

31.  The military use radar to detect enemy
artillery as well as their own machinery
 They can show where their vehicles and
soldiers are in relation to enemy machines

32.  Used to study the Earth's ionosphere and its
interactions with the upper atmosphere, the
magnetosphere, and the solar wind .

33.  Electrons in ionosphere
are radar targets
These electrons can
scatter radio waves

34.  The strength of the echo received from the
ionosphere measures the number of
electrons able to scatter radio waves or what
we call electron.

35.  Some electrons are moving
due to heat - In this case
the echo is scattered
 The echo will contain a
range of frequency close
to the transmitter
frequency
 As the temperature
increases, the electrons
move faster
 So radar can act like a
thermometer and measure
the temperature of the
ionosphere

36.  When an electron is
removed from an atom,
the remaining charged
atom is called an ion
 The ion gas can have a
different temperature
from the electron gas
 The electron/ion mixture
is known as a plasma and
is usually in motion (like
our wind)
 So incoherent scatter
radar can also measure
wind speed

38.  The US Military is currently using
groundbreaking radar
 This radar allows soldiers to see objects and
people through walls

39.  Technology will continue to grow, and radar
will advance with it
 Growth of radar technologies will be
accompanied by a wider variety of
applications
 Radar in the future will most likely be as
common as cell phone applications are today
 LIDAR is advanced type of radar which uses
visible light from laser.

40.  REFERENCES
 M. Kulkarni, “Microwave and Radar
Engineering”, 3rd edition, Umesh
Publication, 2003, pp. 493 – 536
 Merri.I.skolnik, “Intoduction to Radar
System”, 3rd edition, Tata McGraw
Hill, 2003
 “Types of Radar”, Engineers
Garage,2012[online]. Available:
http://www.engineersgaragee.
 com/articles/type-of-radars
[accessed: September 2012]