Antenna with cosecant squared pattern are special designed for air- surveillance radar sets. These permit an adapted distribution of the radiation in the beam. a fan beam. Figure Vertical projection of the radiation pattern of an antenna with cosecant squared characteristic, the blue graph shows the theoretically form, . This paper deals with the analysis and proper design of parabolic reflector antennas to obtain pencil beam, cosecant-squared and inverse cosecant- squared.
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This gives in near range an additional gain required for constant echo strength after sensitivity time control.
The cosecant squared pattern isn’t restricted to parabolic reflectors. This antenna uses a polar coordinate system. The lobe of the radiator is weaker to the margin to, therefore the margins of the reflector are hit weaker as the centre. The angle m in the above equation and illustration.
Cosecant squared antenna
From Wikipedia, the free encyclopedia. It is equal to the reciprocal value of the sine function. The result was an evener display pattern. The slant range distance between the radar and the terrain is the cosecant of the angle between the fuselage and the target, and the energy falls off with the fourth root of that cosexant. The concept originated as part of the development of the H2S radarwhich scanned the area under an aircraft to provide a radar map of the ground below.
You can specify the following parameters: However, what does this term have to antfnna with our antenna?
Stacked beam cosecant squared pattern. Views Read Edit View history. Parameter Description Alpha 1 Angle The angle 1 in the above equation and illustration.
A possibility consists in lower bending of the top of the reflector. By the fact that the rays turned up don’t have a large power density, the maximum range in the higher elevation is limited with that. A radiator is in the focal point of a parabolic reflector and produces a relatively sharply bundled radiation lobe since the rays leave the reflector parallelly in the ideal case.
Radar Basics – Antennae with Cosecant Squared Pattern
squxred In the practice a cosecant squared pattern can be achieved by a deformation of a parabolic reflector. However, when computing the antenna’s gain matrix or a link budget, etc. Cosecant-squared pattern achieved by displacing the reflector square from the original parabolic shape. Azimuth Beamwidth The full width of the beam in the x-y plane of the beam coordinate system. Design Frequency The frequency of the antenna.
The terrain at further distances returns much less signal due to the radar equation.
Cosecant squared antenna – Wikipedia
This page was ocsecant edited on 30 Decemberat Vertical projection of the radiation pattern of an antenna with cosecant squared characteristic. To get the cosecant squared pattern, a part of the radiated energy must be turned up.
Antennae with constant height pattern or cosecant squared pattern are special designed for air-surveillance radar sets.
It also illustrates that:. Retrieved from ” https: In reality, the diagram is superposed with a number of side lobes mainly on the back at higher elevation angles. It is shaped to send more radio energy in certain directions in order to smooth out the reception pattern of objects as their range changes in squard to the radar. Open topic with navigation.
It also illustrates that: The ideal pattern as shown in Figure 1 is a nearly rectangular shape with rounded corners. Main-lobe Gain dB The main lobe gain of the antenna pattern.
Alpha M Angle The angle m in the above equation and illustration. To counteract this, the scanning antenna was re-aimed so that it was pointed almost directly forward, thereby sending most of the radar energy at low angles relative to the aircraft, thereby increasing the energy available at long range.