This document provides an introduction to radar communication. It begins with defining radar as using radio waves for detection and ranging of targets. It then explains the basic principle of radar by comparing it to sound wave reflection. It defines important terms related to radar like range, pulse repetition frequency, maximum unambiguous range, minimum range, and clutters. It describes the different types of radars including pulse radar and continuous wave radar. It explains Doppler effect and how MTI radar uses it to detect moving targets. Applications of radar discussed include weather radar, police radar guns, military radars, and future developments like using TV signals and passive radar.

1. WELCOME

2. Deepa Rani S
Assistant professor in Physics
Govt: College for women
Trivandrum
RADAR COMMUNICATION

3. Contents
 INTRODUCTION
 BASIC PRINCIPLE
 IMPORTANT TERMS
 TYPES OF RADAR
 BASIC RADAR BLOCK DIAGRAM
 DOPPLER EFFECT
 MTI RADAR
 APPLICATIONS

4. INTRODUCTION
RADAR -- Radio Detection and Ranging
 Radio– Radio waves are used
 Detection-- To identify the target
 Ranging– To find the distance or position of the
target
 Founder – First practical radar
-- British Physicist Sir Robert Watson
Watt in 1935
 Father of Radar – Heinrich Hertz -- German
Physicist

5. Basic Principle
 The electronic principle on which radar
operates is very similar to the principle of
sound-wave reflection.
 If you shout in the direction of a sound-
reflecting object (like a rocky canyon or cave),
you will hear an echo.
 If you know the speed of sound in air, you can
then estimate the distance and general
direction of the object

6. Basic Principle

7. Basic Principle

8. IMPORTANT TERMS
 Range
 Pulse Repetition Frequency
 Maximum Unambiguous Range
 Minimum Range
 Clutters

9.  Range
The distance between Radar and target is called
Range of the target or simply range, R
Speed = Distance /Time
Distance = Speed × Time
2R = c × T
R = c × T/2

10.  Pulse Repetition Frequency
The time interval between the successive clock
pulses is called pulse repetition time, TP .The
reciprocal of pulse repetition time is called pulse
repetition frequency, fP
Mathematically, it can be represented as
fP = 1/Tp

11.  Maximum Unambiguous Range
we have to select the duration between the two
clock pulses in such a way that the echo signal
corresponding to present clock pulse will be
received before the next clock pulse starts. Then,
we will get the true range of the target and it is
also called maximum unambiguous range of the
target or simply, maximum unambiguous range.
Run =

12.  Minimum Range
We will get the minimum range of the target,
when we consider the time required for the echo
signal to receive at Radar after the signal being
transmitted from the Radar as pulse width. It is
also called the shortest range of the target.
Rmin =c τ/ 2

13.  Clutters – Unwanted echoes
- unwanted received signals

14. TARGETS
 Stationary- Normal Radars
 Moving– Moving Target Indication Radars
OR
MTI Radar

15. TYPES of Radars
 Pulse Radar
Basic Pulse Radar
Moving Target Indication Radar (MTI)
 Continuous Wave Radar

16. Pulse Radar– Transmitted Wave

17. Continous Wave Radar –
Transmitted Wave

18. BLOCK DIAGRAM

19. MTI RADAR ---DOPPLER
EFFECT

20. MTI RADAR- Doppler effect

21. DOPPLER EFFECT
 If the target is not stationary, then there will be a
change in the frequency of the signal that is
transmitted from the Radar and that is received
by the Radar. This effect is known as the Doppler
effect.
 According to the Doppler effect, we will get the
following two possible cases −
 The frequency of the received signal will
increase, when the target moves towards the
direction of the Radar.
 The frequency of the received signal will
decrease, when the target moves away from the
Radar.

22. fd = 2 vr / λ
fd = Doppler frequency shift
vr = Velocity of the target
λ = Wave length

23.  ft --- Transmitted wave frequency
 ( ft - fd )-- Received wave frequency if the target
is moving away from radar
 ( ft + fd )-- Received wave frequency if the target
is approaching towards radar

24. MTI RADAR – Only for moving
targets

25. APPLICATIONS
 Weather Radar

26. WEATHER RADAR
 The Doppler radar used in weather forecasting
measures the direction and speed, or velocity, of
objects such as drops of precipitation. This is
called the Doppler Effect and is used to
determine whether movement in the atmosphere
is horizontally toward or away from the radar,
which aides in weather forecasting.

28. APPLICATIONS
 Radars in Military

29. POLICE RADAR
 Police RADAR.
RADAR speed detectors bounce microwave
radiation off of moving vehicles and detect the
reflected waves. These waves are shifted in
frequency by the Doppler effect, and the beat
frequency between the directed and reflected
waves provides a measure of the vehicle speed.

30. RADAR GUN
 Radar gun

31.  FUTURE RADARS
 TV Signals Can be Used in Radar Capacity: TV signals’ behavior is
similar to radar, but they operate at different ends of the radio spectrum.
New technology has emerged using receivers tailored to these signals,
and successfully tracked 30 airplanes at a range of 10,000 feet.
And where some radar can confuse wind turbine activity with aircraft,the
TV signals encountered much less interference. TV signal “radar” takes
advantage of broadcast networks that already disseminate the signals.
Using TV signals could mean a radar-like technology that is more cost-
effective than traditional radar to develop and use.
PASSIVE RADAR IN DEVELOPMENT, EXPECTED TO BE A GAME
CHANGER
Passive radar, a different type of radar technology, is set to be the next
big thing in military radar applications. It operates almost in reverse to
existing radar—while radar puts out electromagnetic signals to function,
passive radar takes in existing electromagnetic signals from the
atmosphere to support imaging and tracking capabilities. Passive radar
is less expensive to operate and is more covert than traditional radar.
The global passive radar market is expected to hit $10 Billion USD in
annual spending by 2023.

32.  3D radar provides for radar coverage in three
dimensions; unlike the more common 2D radar
which provides range and bearing, the 3D radar
also provides elevation. Applications include
weather monitoring, air defense, and surveillance.

34. THANK YOU