Radar Systems

Radar Systems

• Object Detection• RAdio Detection And Range finding (RADAR)

• Velocity, altitude, direction, shape, distance

• Used for:AircraftShipsMissilesWeatherBird MigrationAutomotiveTerrain MappingNavigationDistance Measurements

Operating Principle

• TX of radio waves in the micro wave spectrum (typically over 3GHz – old systems use VHF and UHF signals)

• RX of reflected signal, direction, shape of reflected signal is evaluated to determine the range and object

Timeline:

• 1886 Concept – Hertz

• 1897 Experiments with ships – Popov

• 1904 Detection of ships in fog – Hulsmeyer

• 1935 Development of “Death Ray” turnedinto aircraft detection radar

• 1940s RADAR technology refined,monopulse systemnavigation systems

• Post War developments:- shorter wavelength- meteorological radar- stealth technology- multi radar systems

Radar Signal

• Bounces of electrical conductive objects

• Shift in frequency occurs if object moves away or is getting closer (doppler effect)

• Signal processing is used to evaluate the reflected signal

• Some materials absorb radar signals, used for stealth vehicles

• Pulse travels at the speed of light, the return signal measured in uS will allow the determination of the presence and distance of an object.

Video (5 Min.)

Radar Signals

The wavelength should be smaller than the object to be identified

• VHF – 30MHz and above – 10m

• UHF – 300MHz and above - 1m

• SHF – 3 GHz and above - 10 cm

• EHF – 30GHz and above – 1cm

• Rain and moisture attenuates signals above 10GHz

Video Marine Radar (3 Min.)

Limitations of RADAR

• Visible horizon

• Noise

• Curvature of the earth

• Material it is reflected from (wooden boats)

• Interference from other radar systems

• Frequency and weather conditions

• Time between pulses to allow for maximum distance

• Clutter

• Jamming

Video (33 Min.)