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MIcrowave and Antenna ppt.pptx
1. RADAR
By Sajjad Al Hossen
Dept: EETE
Roll: 11
Batch: 29th(Day)
Course: Microwave and
Antenna
Presented to:
Lecturer. Shuvon Talukder
and CO.
Dhaka International
University(DIU)
2. • 1900- Sir “Nicola Tesla” suggested that the
reflection of electromagnetic wave could be
used for detecting of moving object
• 1904- “Christian Hulsmeyer” built an
experimental device that could detect nearby
ships in dense fog , which were completely
invisible in naked eye.
• The modern and practical Radar was
developed in secrecy during world war 2.
History- Invention of Radar
3. Introduction
Radar is something that is in
use all around us, although it is
normally invisible. Radar is an
object detection system that uses
radio waves to determine the
Range , Altitude , Direction or
speed of object. It can be used to
detect aircraft, ships, missiles in
a limited range. Radar was
developed in secrecy during
world war 2 by several nations.
The term Radar was coined in
1940 by United States Navy as
acronym for Radio detection and
Ranging
4. How Radar Works
• A radar system has a transmitter that emits
radio waves called radar signals in
predetermined ways.
• When they come into contact with an
object they are usually reflected or
scattered in many direction
• Radar signals are reflected especially well
by materials of considerable electrical
conductivity –mostly metal, sea water and
wet ground
5. Doppler Effect
Frequency shift is caused by motion
that changes the number of
wavelengths between the reflector and
the radar.
Doppler shifts depends upon whether
the radar configuration is active or
passive. Active radar transmits a signal
that is transmitted back to the receiver.
Passive radar depends upon the object
sending a signal to the receiver.
6. Two basic Radars types
• Pulse transmissions
• Continuous wave
Difference between Pulse and Continuous:
Pulse Continuous
1.Single antenna 1.Requires 2 antennas
2.Gives ranges and alt 2.No range or Alt. info
3.Suspectible to jamming 3.High SNR
4.Physical Range 4.More difficult to Jam but
determined by PW and easily deceived.
PRF.
7. Step 1:Transmit
Radars send out
narrow beams of
electromagnetic
radio waves in
short or long pulses
via a transmitter.
8. Step 2: Reflect
Those waves can be
intercepted and reflected
by objects – perhaps a
metal object, like an
aluminum-skinned plane
or missile, or a fluid
object such as
precipitation. The
reflection of the waves
helps radar operators
determine many features
of that object – distance,
direction, speed, shape,
range, etc.
9. Step 3: Receive
The receiver accepts the
returned energy of the radio
waves and measures the time
elapsed since the
transmission. The distance,
or range, of that object is
calculated by measuring the
total time the radar signal
takes to make the trip to the
target and back. By
measuring the location of a
target over time, the target’s
recent track can be
determined; and once
established, the future path
can be predicted.
10. Application of Pulse Radar
Nautical Radars
Aviation Radars
Marine Radars
Weather sensing Radars
Detection and search radars
Target acquisition Radar systems
Missile guidance system
Radar for biological radars
Air traffic control and navigation Radar