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Reflective array 'billboard' antenna of the SCR-270 radar, an early US Army radar system. It consists of 32 horizontal half wave dipoles mounted in front of a 17 m (55 ft) high screen reflector. With an operating frequency of 106 MHz and a wavelength of 3 m (10 ft) this large antenna was required to generate a sufficiently narrow beamwidth to ...
The scale of dBZ values can be seen along the bottom of the image. Decibel relative to Z, or dBZ, is a logarithmic dimensionless technical unit used in radar. It is mostly used in weather radar, to compare the equivalent reflectivity factor (Z) of a remote object (in mm 6 per m 3) to the return of a droplet of rain with a diameter of 1 mm (1 mm 6 per m 3). [1]
A corner reflector for radar testing. A corner reflector is a retroreflector consisting of three mutually perpendicular, intersecting flat reflective surfaces. It reflects waves incident from any direction directly towards the source, but translated.
Planar reflectarray fed by a horn antenna.Structure showing unit cells. [1] This antenna has fixed cell delays, configured by different cutout sizes in each cell, as can be seen in the top-right inset.
Radar cross-section (RCS), denoted σ, also called radar signature, is a measure of how detectable an object is by radar. A larger RCS indicates that an object is more easily detected. [1] An object reflects a limited amount of radar energy back to the source. The factors that influence this include: [1] the material with which the target is made;
A common type of array antenna, a reflective array UHF television antenna.This example consists of eight dipole driven elements mounted in front of a wire screen reflector. . The X-shaped dipoles give it a wide bandwidth to cover both the VHF (174–216 MHz) and UHF (470–700 MHz) TV ban
In the United States NEXRAD network some of these angles are .5, 1.45, 2.4, and 3.35 degrees with the radar having up to 14 angles when it is in Severe Mode. [ 1 ] [ 2 ] In the composite reflectivity product, the highest intensities among those available on the different angles above each point in the image will be displayed.
Because of radar, astronomers can map the contours of far-off planets, physicians can see images of internal organs, meteorologists can measure rain falling in distant places, air travel is hundreds of times safer than travel by road, long-distance telephone calls are cheaper than postage, computers have become ubiquitous and ordinary people ...