This presentation is about Prediction of range performance in radar communication

1. Prediction of range performance
Name – Bhupender Singh
Roll no. – 13ECE06
Subject- RADAR & SONAR engineering

2. Content
• Introduction to radar
• Radar working
• Radar equation
• Use of radar equation
• Prediction of range performance

3. Introduction to radar
• RADAR is acronym for Radio Detection and Ranging.
• First successfully demonstrated in 1936.
• It uses electromagnetic waves.
• Large variety of application.

7. How weather radar works

8. Radar application
• Military
• Air traffic control
• Remote sensing
• Ship safety
• space

9. Radar equation
• Perhaps the single most useful description of the factors influencing radar
performance is the radar equation which gives the range of a radar in terms of the
radar characteristics.
• The radar range equation relates the range of the radar to the characteristics of the
transmitter, receiver, antenna, target and the environment.
• The radar range equation represents the physical dependences of the transmit
power, that is the wave propagation up to the receiving of the echo-signals.
• The radar equation is an important tool for following aspects
1. Assessing the performance of radar
2. Designing of new radar systems
3. Assessing the technical requirements for new radar procurements

11. • -If the transmitter delivers ( ) Watts into an isotropic antenna, then the power
density(W/m2) at a distance R from the radar is
• here the 4πR2 represents the surface area of the sphere at distance R
• the gain G of an antenna is the measure of the increased power radiated in the
direction of the target, compared to the power that would have been radiated
from an isotropic antenna.
Power density from a directional antenna =

12. • the measure of the amount of incident power by the target and redirected
back in the direction of the radar is called the cross section σ.
• Hence the Power density of the echo signal at the radar =
• - the receiving antenna effectively intercepts the power of the echo signal at
the radar over a certain area called the effective area Ae.
• Since the power density (Watts/m2) is intercepted across an area Ae, the
power delivered to the receiver is

13. • - Now the maximum range Rmax is the distance beyond which the target
cannot be detected due to insufficient received power Pr The minimum
power which the receiver can detect is called the minimum detectable
signal Smin.
• Setting Pr= Smin and rearranging the above equation gives
• Note here that we have both the antenna gain on transmit and its
effective area on receive. These are related by:

14. • As long as the radar uses the same antenna for transmission and reception
we have

15. Drawbacks of simple form of radar equation
• The fluctuation and uncertainties in target radar cross section.
• The nature of minimum detectable signal, which is affected by
the receiver noise.
• The losses experienced in the radar system
• Displaying the locating targets is not clear

16. Prediction of range performance
• All of the parameters of the basic pulsed radar system will
affect the performance in some way.
• Some basic factors –
1. Transmitter power
2. Pulse width
3. Pulse repetition frequency (PRF) and range ambiguities
4. Radar operating frequency

17. Transmitter power

18. Pulse width ( PW )
• The duration of the pulse and the length of the target along the radial directions
determine of the returned pulse.
• The range of values from the leading edge to the trailing edge will create some
uncertainty in the range of the target.

19. If we designate the uncertainty in measured range as the range resolution,
Rres, then it must be equal to the range equivalent of the pulse width.
To create perfectly formed pulse with a vertical leading edge would require an
infinite bandwidth. In fact you may equate the bandwidth β, of the transmitter
to the minimum pulse width,
PW by :

20. Pulse repetition frequency (PRF) and range ambiguities
• PRF is crucial for systems and devices that measure distance.
1. RADAR
2. LASER RANGE FINDER
3. Sonar
• Different PRF allow systems to perform very different functions.
• A radar system uses a radio frequency electromagnetic signal
reflected from a target to determine information about that target.
• PRF is required for radar operation. This is the rate at which
transmitter pulses are sent into air or space.

22. Radar operating frequency
• The frequency of the radio carrier wave will also have some affect on how
the radar beam propagate.
• For low frequency, at the high extreme, the radar beam will behave much
like visible light and travel in very straight line.
• Very high frequency radar beams will suffer high losses and are not suitable
for long range systems.

24. Thanky u