Radar History In Brief

In 1924 Sir Edward Victor Appleton used radio echoes to determine the height of the ionosphere, but the first practical radar system was produced by Sir Robert Watson-Watt in 1935 [3]. By 1939 England had established a chain of radar stations along its south and east coasts (“Home Chain”).
Basic Working Principle Of Radar
The antenna collects the echo signal energy and delivers it to the receiver. Through signal amplification and processing the radar receiver produces data to a computer and/or a visual signal on an indicator screen, such as a computer display monitor.
Information Provided By Radar


The most essential parameters provided by radar echoes are: Range Relative velocity Angular direction （方向角） Target size Target shape
Radar History In Brief
The first radar is claimed
to be invent Christian Hiilsnieyer in 1904, developed for traffic supervision on the river Rhine.
Christian Hülsmeyer produced the first practical radar patented in 1904 (Pic. 1.3 - D.M.M)
Basic Working Principle Of Radar
Radar basically involves transmitting a burst of electromagnetic energy by means of an antenna, which concentrates the waves into a shaped beam pointing in the desired direction. When these transmitted signals strike an object in the path of the beam, a tiny fraction of the total energy is reflected to form an echo signal.
Radar History In Brief

During the 1980s and 1990s, due to the developments of novel solid-state electronics and the escalating availability of inexpensive powerful data processing equipment, innovative modulation methods, signal generation and processing techniques have gradually been applied to radar system, which had been a great breakthrough.
Information Provided By Radar

Modern radars are capable of providing a lot more information about a target. The extent of information about the target derived by the radar depends on the transmitted and received waveform parameters, such as amplitude, frequency and phase, and on the vector nature of the electromagnetic waves,—polarization.
Applications

the technique of radar has been extensively applied into some fields, including Military, Meteorology, Topographic survey. It is mainly used for navigation, remote or early warning, guidance, battlefield surveillance and so on.
Radar
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Basic introduction of radar; History of radar； Information Provided By Radar; Applications of radar;
Basic Introduction
Radar History In Brief
James Clerk Maxwell predicted the existence of radio waves in his theory of electromagnetism as long ago as 1864. He showed mathematically that all electromagnetic waves travel at the same velocity in free space, independent of their wavelength, and this velocity is as same as the speed of light.

RADAR is a term which is coined as an acronym(缩略词) for RAdio Detection And Ranging.
Basic Introduction
Radar mainly consists of a transmitter, a receiver, antennas,signal processor and an indicator screen. Duplexer(双工器)
Range

The range R is derived from the time delay of the signal, the two pertinent parameters being linked by the velocity of light c through:


The maximum detectable range is limited by noise, either incoherent noise being independent of the signal or signal coherent noise
electromagnetism (Pic. 1.1 - J.C.M.F)
Radar History In Brief
In 1886 Heinrich Rudolf Hertz verified Maxwells equations through laboratory experiments, where he found that radio waves could be transmitted through different materials, whereas being (partly) reflected at the surface of an object.
Radar History In Brief
Before radar could be born, scientists needed to understand the behaviour of electromagnetic waves according to the James Clerk Maxwell fundamental equations developed predicted the existence radio waves in his by James Clerk Maxwell around 1864. of theory of
Heinrich Hertz –Hertz confirmed by experiment that electromagnetic radio waves have the same velocity as light and can be reflected by metallic and dielectric bodies (Pic. 1.2 I.N.T)
Angular direction
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The angular direction may be obtained by using a rotating antenna, or by measuring the phase difference of received signals from different (array) antenna elements.