RADARRadar (radio amplification detection and ranging) is anelectronic system for transmitting electromagnetic signalsand receiving echoes from objects of interest (targets).
HISTORY OF RADAR• Invented in1900s(Patentedin 1904)• Implemented inWorld war 2• Installed onships fordetecting enemy
HOW A RADAR WORKSTransmits anelectromagneticsignal modulatedwith particulartype of waveform.(modulationdepends onrequirements ofapplication)Signal is reflectedfrom targetReflected signal isdetected by radarreceiver andanalyzed to extractdesired information
TYPES OF RADARDetection and search radarsMissile guidance systemsBattlefield and reconnaissance radarAir Traffic Control and navigationSpace and range instrumentation radar systemsWeather-sensing Radar systemsRadars for biological research
Radar Frequency BandsFrequencyWavelength 1 mm1 km 1 m 1 m 1 nm1 MHz 1 GHzIR UV109 Hz0 1 2 3 4 5 6 7 8 9 10 11 1230 20 10 8 6 5 4 39 7Allocated Frequency (GHz)Wavelength (cm)X-BandC-BandS-BandL-BandUHFVHFVisible1012 HzKuKKaW
Target• Target range =c2where c = speed of light= round trip timeRADAR RANGE MEASUREMENT
RADAR APPLICATIONS• AIR TRAFFIC CONTROL• AIR NAVIGATION• REMOTE SENSING• MARINE• LAW ENFORCEMENT AND HIGHWAY SAFETY• SPACE• MILITARY
• Basic Radar Range Equation - Monostatic– Usually the same antenna is used for transmission andreception and we have the relationship between Gain andeffective area:–
LATEST TECHNOLOGIES IN RADAR• STEALTH• SYNTHETIC APERTURE RADAR• MTI RADARS• MESA TECHNOLOGY• AIRBORNE METHOD• SATELLITE BASED METHOD
FOR REDUCING RADAR DETECTION• The sea water is used to make the ships less detected as they are goodreflectors.
AIRBORNE METHOD• USEFUL TO DETECT ENEMY IN 3-D• THEY USE LIDAR• MADE TO FLY HIGH UP IN THE AIR
SATELLITE BASED METHOD• THE SATELLITE USE RADAR SENSORS• THEY COVER A WIDE AREA• THEY ARE MORE RELIEBLE AND SAFE
SURFACE BASED METHODS Radars of high sensitivity are used, like Radio Telescopes. They work good at all weather conditions. They use the concept of Radio-Astronomy. Requires heavy installations. The speed & trajectory of the enemy can be easily detected. Can detect he difference between hostile & Stealth crafts. Destroy the enemy with out their notice. Do not release radio signals.