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Applications of Radar

Basic Concepts

Definition

Radar RAdio Detection And Ranging. A system that uses reflected electromagnetic

radiation to determine the velocity and location of a targeted object; widely used in such

applications as aircraft and ship navigation, military reconnaissance, automobile speedchecks, and weather observations.

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The transmitter generates the radio waves which are radiated by one of the antennas

whilst the receiver antenna listens for the echos of these waves. If a target is detected a

blip occurs on the display. In practice the receiver and the transmitter often share thesame antenna.

Radar History

Sir Henry Tizard Robert Watson-Watt

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Applications

Hazardous Weather Detection

Storm avoidance Windshear warning

Navigational Aid

Marking remote facilities

Facilitating air traffic control

Avoiding air-to-air collisions

Blind low altitude flight

Forward velocity update

Precision velocity update

Ground Mapping

Ice patrol

Terrain mapping

Environmental Monitoring

Law enforcement

Blind landing guidance

Short- Range Sea Search

Search and rescue

Submarine detection

Reconaissance/Surveillance

Long-range surveillance

Early warning

Sea surveillance

Ground battle management

Low-altitude survellance

Fighter/Interceptor Support

Air- to air search

Raid assessment

Target identification

Gun/missile control

Missile guidance

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Air/Ground Weapon Delivery

Blind tactical bombing

Strategic bombing

Defence suppression

Proximity Fuses

Artillery

Guided missile

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Operating frequency: 1275 MHz

Peak power: 1 kW at feed

Antenna diameter: 25 m

Beam width: 0.75Pulse repetition frequency: 3125 Hz (typical)

Minimum range: 1.8 km (typical)

Maximum range: 48 km (typical)

Pulse duration: 0.8 s x 8 bits (typical)

Range resolution: 60 m

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Clear Air radar

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Swiss Air Traffic Control Radar

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Wind Shear Radar

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Ice patrol

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Fylingdales- the old

and the new

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Australian Air Force Airborne Early Warning System

An Active Electronically Scanned Array L band

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Patriot Radar operating frequency 4-6GHz. Phased array with 5000

elements that can track 100 objects at distances of 100Km

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Frequencies used for Radar

It depends on a large number of factors including

Physical Size

In order to transmit and generate RF power the dimensions of the hardware must be

similar to the wavelength. A 30cm radar is going to be large

Transmitted Power

High power radar are usually low frequency because of size of hardware needed.

Difficult to dissipate heat and restrict gradients if components are small

Beamwidth

Atmospheric Attenuation

Absorption and scattering by the atmospheric gases particularly oxygen and watervapour. Below 0.1GHz absorption is negligible. Above 20GHz it can be severe.

Scattering is proportional to particles dielectric constant and the size of the particle

relative to the wavelength. The scattering by hail, smoke, dust is low because thedielectric constant is low

Doppler

The higher the frequency of the radar used the greater will be the shift in frequency for a

motion of the target and the more sensitive. Excessive Doppler shifts can cause problems

Typical Frequency SelectionEarly Warning Radar UHF and S band

Radar Altimeters C-bandWeather Radars C and X-bands

Fighter/Attack X and Ku bands

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Federal Spectrum Requirement Forecast for Radar Bands

Frequency Bands

92-100 GHz Airborne fire-control, beacons, atmospheric research, cloud

detection, and synthetic vision radars31.8-36 GHz Airborne navigational, mapping, weather, beacon, terrain

following & avoidance; aircraft carrier PAR, test range,

atmospheric & oceanic research, altimeter, scatterometer, andsynthetic vision radars

24.05-24.65 GHz Doppler radiolocation, vehicle speed detection, scatterometer, and

precipitation radars15.4-17.3 GHz Airborne and shipborne multimode search, battlefield, aircraft

carrier PAR, fire-control, test range, ASDE,

scatterometer, precipitation, atmospheric research, and spaceborne

radars

13.25-14.2GHz Airborne and shipborne search and acquisition Doppler, airborneweather, altimeters, scatterometer, precipitation, environmental

research, and spaceborne radars8.5-10.55 GHz Airborne and shipborne surveillance and navigation, fire-control,

battlefield, maritime, weather, test range, airborne

radionavigation, ATC, SAR's, altimeters, ASDE, scatterometer,vehicle speed detection, and spaceborne radars

5250-5925 MHz NOAA weather radars, FAA TDWR, surveillance and air defense

(airborne, shipborne, land-based), fire-control,maritime, test range, SAR's, altimeters, scatterometer, airborne,

and spaceborne radars

4200-4400 MHz Aircraft radar altimeters3100-3650 MHz DOD surveillance and air defense (airborne, shipborne, land-

based), ATC, SAR's, altimeters, test range, and spaceborne radars

2700-3100 MHz ATC, maritime, and weather radars; DOD shipborne, airborne,

ground air surveillance radars; range control, and spaceborneradars

2310-2385 MHz Planetary and lunar radar

1215-1390 MHz ATC, SAR's, and DOD early warning air defense, battlefield,shipborne long-range surveillance, and spaceborne

radars

890-942 MHz Navy shipborne long-range surveillance, test range, NASA

research, and wind profiler radars420-450 MHz DOD early warning and long-range surveillance radars; and wind

profiler radars

216-220 MHz DOD space surveillance radar3-30 MHz DOD OTH and surface wave radar

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