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radar:introduction

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radar:introduction [2018/06/08 11:34] – iatcoradar:introduction [2026/04/28 15:13] (current) – external edit 127.0.0.1
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 <figure fig1> <figure fig1>
 {{ :media:radar_operating_principle.png?300 |}} \\  {{ :media:radar_operating_principle.png?300 |}} \\ 
-<caption>Radar operating principle</caption>+<caption>Radar operating principle.</caption>
 </figure> </figure>
 Synthetically, the operation of the radar is quite simple. In fact, thanks to the properties of the electromagnetic waves, that are reflected if they meet an electrically conductive surface and knowing the constant speed of the light that travels through the air $c=299792458\;m/s$, in practice it will be assumed $c\simeq300\;m/ \mu s$, we can compute the distance between the radar and the target. Obviously it's also necessary to know the elapsed time interval between the transmitted signal and the received echo.\\  Synthetically, the operation of the radar is quite simple. In fact, thanks to the properties of the electromagnetic waves, that are reflected if they meet an electrically conductive surface and knowing the constant speed of the light that travels through the air $c=299792458\;m/s$, in practice it will be assumed $c\simeq300\;m/ \mu s$, we can compute the distance between the radar and the target. Obviously it's also necessary to know the elapsed time interval between the transmitted signal and the received echo.\\ 
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 <figure fig2> <figure fig2>
 {{ :media:typical_block_diagram_radar_.png?600 |}} {{ :media:typical_block_diagram_radar_.png?600 |}}
-<caption>Typical block diagram of a radar+<caption>Typical block diagram of a radar.
 [(cite:TTR>Gaspare Galati (2009), Teoria e Tecnica Radar.)] [(cite:TTR>Gaspare Galati (2009), Teoria e Tecnica Radar.)]
 </caption> </caption>
 </figure> </figure>
 \\  \\ 
-This is the most used radar configuration, where the antenna used for transmission and reception is the same. As we can see after the antenna there is a de-coupling device between the TX and RX subsystems. This device called //Duplexer// is able to switch between the two functionalities of the antenna. This switching is necessary because the high-power pulses of the transmitter would destroy the receiver if energy was allowed to enter in the receiver. The transmitter is able to produce pulses of high-power, that will be propagated in the direction pointed by the antenna. \\ +This is the most used radar configuration, where the antenna used for transmission and reception is the same. As we can see after the antenna there is a de-coupling device between the TX and RX subsystems. This device called //Duplexer// is able to switch between the two functionalities of the antenna. This switching is necessary because the high-power pulses of the transmitter would destroy the receiver if the energy was allowed to enter in the receiver. The transmitter is able to produce pulses of high-power, that will be propagated in the direction pointed by the antenna. \\ 
 The received RF-signal is processed through amplification, demodulation and other techniques that we will see later. Finally the obtained data are shown to the user.  The received RF-signal is processed through amplification, demodulation and other techniques that we will see later. Finally the obtained data are shown to the user. 
 \\ \\  \\ \\ 
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 |$W$   |75-110 GHz   |    |$W$   |75-110 GHz   |   
 |$mm$   |110-300 GHz   |   |$mm$   |110-300 GHz   |  
-<caption>Denomination of frequency ranges, IEEE Std. 521,1984</caption>+<caption>Denomination of frequency ranges, IEEE Std. 521,1984.</caption>
 </table> </table>
  
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 In general it's used for medium and short distance surveillance applications. In this band the influence of bad weather conditions is very high and the use is predetermined for most types of weather radar, used to locate precipitation in temperate zones like Europe.\\ \\  In general it's used for medium and short distance surveillance applications. In this band the influence of bad weather conditions is very high and the use is predetermined for most types of weather radar, used to locate precipitation in temperate zones like Europe.\\ \\ 
 **$X$**\\  **$X$**\\ 
-Thanks to the short wave length the use of this band allows to realize devices with reduced cost, size and weight, ideal for mobile applications. This frequency band is widely used for maritime civil, military navigation and +Thanks to the short wave length the use of this band allows to realize devices with reduced cost and size, ideal for mobile applications. This frequency band is widely used for maritime civil, military navigation and 
 for airport surface traffic control radars. Very small and cheap antennas with a high rotation speed allow a good accuracy. A long range is not a major requirement for these applications.\\ \\  for airport surface traffic control radars. Very small and cheap antennas with a high rotation speed allow a good accuracy. A long range is not a major requirement for these applications.\\ \\ 
 **$K$,$K_u$ and $K_a$**\\  **$K$,$K_u$ and $K_a$**\\ 
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 <figure milrad > <figure milrad >
 {{ :media:military_radar1.jpg?600 |}} {{ :media:military_radar1.jpg?600 |}}
-<caption>Military Radar+<caption>Military Radar.
 [(cite:site1>https://commons.wikimedia.org/wiki/Main_Page and http://www.eldis.cz/en/rl-2000-primary-surveillance-radar)] [(cite:site1>https://commons.wikimedia.org/wiki/Main_Page and http://www.eldis.cz/en/rl-2000-primary-surveillance-radar)]
 </caption> </caption>
 </figure> </figure>
 In Figure {{ref>milrad}} there are some examples of military radar, and as we can see they can be use different kinds of antenna; phased array, parabolic reflector and array of dipoles.\\  In Figure {{ref>milrad}} there are some examples of military radar, and as we can see they can be use different kinds of antenna; phased array, parabolic reflector and array of dipoles.\\ 
-In Air Traffic Control the radars are used to control the traffic near airports, to detect and display the aircraft’s position in the airport terminals and to guide the aircraft to land in bad weather using Precision Approach RADAR. But they can be used not only for aircraft, another application is to scan the airport surface for identify the vehicles positions.\\ +In Air Traffic Control the radars are used to control the traffic near airports, to detect and display the aircraft’s position in the airport terminals and to guide the aircraft to land in bad weather conditions. But they can be used not only for aircraft, another application is to scan the airport surface for identify the vehicles positions.\\ 
 In Remote sensing radars are used to obtain information on the environment. They are used to observe the weather, the planetary position, monitor sea ice and the ground. In remote sensing radar applications using the Synthetic Aperture Radars (SAR) instruments, it's possible to produce images using radio waves. Below in Figure {{ref>sarimg}} is shown an example of SAR images taken over the Capitol Building of Washington. In Remote sensing radars are used to obtain information on the environment. They are used to observe the weather, the planetary position, monitor sea ice and the ground. In remote sensing radar applications using the Synthetic Aperture Radars (SAR) instruments, it's possible to produce images using radio waves. Below in Figure {{ref>sarimg}} is shown an example of SAR images taken over the Capitol Building of Washington.
 <figure sarimg>          <figure sarimg>         
 {{ :media:sar_capitol_washington.jpg?400 |}} {{ :media:sar_capitol_washington.jpg?400 |}}
-<caption>SAR image of Capitol Building, Washington+<caption>SAR image of Capitol Building, Washington.
 [(cite:site2>https://www.eas.ee/kosmos/et/estonian-space-office/news/article/444-tartu-observatory-works-on-synthetic-aperture-radar-applications)] [(cite:site2>https://www.eas.ee/kosmos/et/estonian-space-office/news/article/444-tartu-observatory-works-on-synthetic-aperture-radar-applications)]
 </caption> </caption>
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 <figure fig5> <figure fig5>
 {{ :media:automotive_radar.jpg?600 |}}  {{ :media:automotive_radar.jpg?600 |}} 
-<caption>Automotive Radar+<caption>Automotive Radar.
 [(cite:site3>http://www.automotive-technology.co.uk/?p=1450 and https://www.rfglobalnet.com/doc/automotive-radars-antenna-design-integration-and-channel-modelling-0001)] [(cite:site3>http://www.automotive-technology.co.uk/?p=1450 and https://www.rfglobalnet.com/doc/automotive-radars-antenna-design-integration-and-channel-modelling-0001)]
 </caption> </caption>
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 <figure fig6> <figure fig6>
 {{ :media:schema_bistatic_radar.jpg?400 |}} {{ :media:schema_bistatic_radar.jpg?400 |}}
-<caption>Operation principle of bistatic radar+<caption>Operation principle of bistatic radar.
 </caption> </caption>
 </figure> </figure>
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 <figure pulsrad> <figure pulsrad>
 {{ :media:pulsed_radar.jpg?500 |}} {{ :media:pulsed_radar.jpg?500 |}}
-<caption>Pulsed radar waveform [(cite:TTR)]</caption>+<caption>Pulsed radar waveform. [(cite:TTR)]</caption>
 </figure> </figure>
  
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 <figure fig7> <figure fig7>
 {{ :media:cw_radar.jpg?500 |}} {{ :media:cw_radar.jpg?500 |}}
-<caption>Typical block diagram of a CW radar+<caption>Typical block diagram of a CW radar.
 [(cite:TTR)] [(cite:TTR)]
 </caption> </caption>
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 <figure> <figure>
 {{ :media:fmcw_radar_distance_measurement.jpeg?400 |}} {{ :media:fmcw_radar_distance_measurement.jpeg?400 |}}
-<caption>Distance measurement in a FMCW Radar+<caption>Distance measurement in a FMCW Radar.
 [(cite:TTR)] [(cite:TTR)]
 </caption> </caption>
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 <figure mopa> <figure mopa>
 {{ :media:mopa.jpg?500 |}} {{ :media:mopa.jpg?500 |}}
-<caption>Radar with MOPA chain [(cite:TTR)]</caption>+<caption>Radar with MOPA chain. [(cite:TTR)]</caption>
 </figure> </figure>
  
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 <figure noncohe> <figure noncohe>
 {{ :media:non_cohe_rad.jpg?500 |}} {{ :media:non_cohe_rad.jpg?500 |}}
-<caption>Non-coherent radar schema[(cite:TTR)]</caption>+<caption>Non-coherent radar schema.[(cite:TTR)]</caption>
 </figure> </figure>
  
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