block diagram of radar and its range equation

8/3/2019 Block Diagram of Radar and Its Range Equation

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BLOCK DIAGRAM OF

RADAR

ANDITS RANGE EQUATION

Presented By:Antarpreet Singh

90600415022


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RADAR

RAdio Detection And Ranging

an object-detection system which uses

radio waves to determine the range,altitude, direction, or speed of object

operates by transmitting a particular

type of waveform and detecting the

nature of the signals reflected back from

objects


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SIMPLE RADAR

Consists of

Transmitter unit

AntennaEnergy detecting receiver

processor


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BLOCK DIAGRAM OF

SIMPLE RADAR


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A portion of the transmitted signal is

received by a reflecting object (target)and is reradiated in all directions.

The antenna collects the returned

energy in the backward direction anddelivers it to the receiver.

The distance to the receiver is

determined by measuring the time

taken for the electromagnetic signal to

travel to the target and back.


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BLOCK DIAGRAM OF

IMPROVED RADAR

A modified block diagram has another

important block called the duplexer


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RADAR RANGE EQUATION

The radar range equation relates the

range of the radar to the characteristics

of the transmitter, receiver, antenna,

target and the environment.

It is used as a tool to help in specifying

radar subsystem specifications in the

design phase of a program.


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Free space condition implies that the radar set

and the target are isolated in an unbounded

empty space.

Conditions to be fulfilled:

No large obstacles lie between antenna and the

target

No alternative transmission path via any reflectingsurface

The intervening medium is transparent, i.e., it does

not absorb energy from the electromagnetic waves at

the frequency used. The intervening medium is homogeneous with

respect to the refractive index at the radar frequency.


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Power (W) delivered by transmitter to

antenna = PT

Power Density (W/m2) at distance R from

the radar = PT/4R2

4R2 Surface area of the sphere

GT Gain of an antenna i.e. the

measure of the increased power radiated in

the direction of the target

Power Density from a antenna = PTGT/4R2


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This energy is incident on the target and

gets scattered in various directions

A part of the energy returns in thedirection of the radar antennas

The effective echo area of the target is

Power Density of the echo signal at theRadar = (PTGT/4R

2 ).(/4R2 )

The receiving antenna effectively

intercepts the power of the echo signal atthe radar over a certain area called the

effective Area Ae


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Since the power density (W/m2) is intercepted

across an area AePower delivered to the receiver =

PTGT Ae/(4R2 )2

This is Free Space Radar Equation

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


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block diagram of radar and its range equation

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