INTRODUCTION TO RADAR SYSTEMS, Merrill I. Skolnik, Third EditionChapter 1 Third Edition By : Merrill I. Skolnik INTRODUCTION TO RADAR SYSTEMS Second Edition

INTRODUCTION TO RADAR SYSTEMS , Merrill I. Skolnik , Third Edition Chapter 1

Third Edition By : Merrill I. Skolnik

INTRODUCTION TO RADAR SYSTEMS

Second Edition By : Merrill I. Skolnik


INTRODUCTION TO RADAR SYSTEMS

Chapter 1:A Introduction to Radar

Third Edition By : Merrill I. Skolnik


Contents

Chapter 1: An Introduction to Radar Chapter 2: The Radar Equation Chapter 3: MTI and Pulse Doppler Radar Chapter 4: Tracking Radar Chapter 5: Detection of Signals in Noise Chapter 6: Information from radar Signals Chapter 7: Radar Clutter Chapter 8: Propagation of Radar Waves Chapter 9: The Radar Antenna Chapter 10: Radar Transmitters Chapter 11: Radar Receiver


What is the Radar?


What is the Radar?


What is the Radar?


What is the Radar?


Radar Advantages

Cloud and smoke penetration. Night vision. Forest canopy penetration and canopy structure. Complements visible/infrared sensors (sensitive to terrain features and moisture). Good for discrimination of terrain structure (roughness) and drainage patterns.

Radar Disadvantages Interpretation requires knowledge of radar interaction with surfaces. Speckle (dark and bright pixels) limits interpretation. Satellite systems are not yet multispectral and multi polarization (usually one band/one polarization) on most satellite platforms (limits forest canopy information).

Not good for discrimination and mapping of different vegetation types except at very general levels. Data analysis can be hindered in steep topography and rough terrain due to extreme layover effects.


Review of Common Radar Types

• CW• Simple Pulsed Range Radar• Pulse Doppler• Pulse Compression (Chirp and Phase Coded)• Frequency Agile• MTI (Coherent and Coherent-on-Receiver)• Mono-pulse• Phased Array• SAR• Bi-static Radars• Instrumentation• Multimode• Other (MLS, ILS, TACAN)


History of the radar

• Before World War II: A simple radar by several country is proposed and applied.

• After World War II: the radar technology grew rapidly.

• Use of Doppler effect in MTI (moving target indicator).• Use of High power stable amplifier such as klystron, TWT and solid state amplifier

instead of the magnetron tube.• Use of mono-pulse radar for better accuracy.• Use of pulse compression technique to achieve the range resolution.• Use of Synthetic aperture radar (SAR) for imaging of ground surfaces. • Development of Airborne radar.• Phase array Antenna for electronically scan of environments without mechanical

movement of the antenna.• Use of HF over-the-Horizon radars to detect aircraft to almost 2000 nmi.• Use of radar technology to recognize target by extraction of its information.• radar to gather weather information, wind speed and direction. • Use of digital signal processing to develop radar.


The Principle of the Radar

RTcR 2

R

smc /103 8

For example : KmRmTR 150sec1


Typical Radar Waveform

PRI (Pulse Repetition Interval)PRF (Pulse Repetition Frequency)

width pulseisPRI

CycleDuty

Pt is Peak Power

Pav is Average Power

KHzPRFmPRI 1sec1

001.0sec1sec,1 CycleDutymPRI

tav PPRI

P

for example:

KWattsPMWattsP avt 11

PRI

1 PRF


Typical Radar Waveform

9010

10log10

3

12

Target echo is : Watts = dBm 1210


IEEE Standard Radar Frequencies


Optical Region


Radar Block Diagram


Plan Position Indicator (PPI) Display


Antenna Pattern

D

65Beam width =

For example : GHzfandmD 35

.deg3.15

1.065 BW

D is Horizontal or Vertical dimension of antenna

cmmf

c101.0

103

1039

8


The Radar Equation

24 R

GPP t

Rindensity

RXTX ,

tP

RGAe ,

22 4.

4 RR

GPP t

TXindensity

Target

et

eTXindensityr ARR

GPAPP .

4.

4.

22

4

1

min2maxmin )4(

S

AGPRSPif et

r

AAAG aee

,

42

4

1

min2

2

max2 4

4

S

APRAG et

e

TX is transmitter

RX is receiverG is gain of antenna

eA is effective aperture of antenna

tP is peak power

is radar cross section

R is distance (range) of target from radar


Example :

P 1.2 A ground-based air-surveillance radar operate at frequency of 1300MHz (L-Band). Its maximum range is 200nmi (1 nautical mile equal 1852meter) for the detection of a target with a radar cross section of 1m2. its antenna 12 m wide by 4 m high, and the antenna aperture efficiency is 0.65. the minimum detectable signal is 10-13 watts. Determine the following:

1. Antenna effective aperture and gain?2. Peak transmitter power?3. Pulse repetition frequency (PRF) to achieve a maximum unambiguous range of 200 nmi?4. Average transmitter power , if the pulse width is 2 micro sec?5. Duty cycle?6. Horizontal and vertical beam width?


Solution :

90.73622.312307.0

4422

eAG

,2.3141265.0.1 2mmmAAe mf

c2307.0

101300

1036

8

dBGdB 67.38)90.7362log(10

et A

RR

GPS .

4.

4.2

22min

MWattsSAG

RP

et 5.1210

2.32190.7362

185220044 1322

min

22

HzmR

cf

f

cTcR PRF

PRF

40418522002

103

22.3

8

sec47.2

404

1mPRI

KWattsPPRI

P tav 12.10105.121047.2

102.4 6

3

6

0008.010097.81047.2

102.5 4

3

6

PRIDuty

.deg24.112

2307.06565.6

DHBW

.deg74.34

2307.06565,

DVBW


Applications of the Radar

• Military Applications Space Systems Airborne Applications Maritime Applications Surveillance Search and Track Fire Control Navigation Missile Guidance Proximity Fuses Altimeter Terrain Avoidance Weather Mapping

• Civil Applications Space Systems Air Transport and Navigation Applications Maritime Applications Industry Applications. Speed and distance measurements Oil and Gas Exploration The movement of insects and birds.












High Resolution Radars


New Radar systems

1. Enhanced Meteorological Radars. [Nexrad, Terminal Doppler Weather Radar, Wind profiler, TRMM satellite weather radar and airborne wind-shear detection radar]

2. Planetary Explorations. [ Magellan for Venus, Cassini for Titan, a moon of Saturn]

3. Interferomectic Synthetic Aperture Radar (SAR) for 3D images.

4. Inverse Synthetic Aperture Radar (ISAR).

5. Ground Penetration Radar (GPR).

6. Serial production of phased array radars. [Patriod, Aegis, Pave Paws, B-1B bomber]

7. Active aperture phased arrays.

8. Ballistic missile defense radars. [GBR and Arrow]

9. HF over the horizon radars. [ROTHR and Jindalee]

10. Battlefield surveillance. [JSTARS]

11. Radars for remote sensing of the environments.

12. Improved air-traffic control radars.

13. New multifunction airborne military fighter/attack radars.


Documents

INTRODUCTION TO RADAR SYSTEMS, Merrill I. Skolnik, Third EditionChapter 1 Third Edition By : Merrill I. Skolnik INTRODUCTION TO RADAR SYSTEMS Second Edition