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Dwell time (T D) in surveillance radar is the time that an antenna beam spends on a target. [1] The dwell time of a 2D–search radar depends predominantly on the antenna's horizontal beam width θ AZ, and; the turn speed n of the antenna (in rotations per minute or rpm, i.e. 360 degrees in 60 seconds = multiplied by a factor of 6).
For example, consider a radar with a beam width of one degree and an antenna that rotates once every ten seconds, or 36 degrees per second. An object will be painted by the beam for only 1/36 of a second as the one-degree beam sweeps over it. If the radar has a PRF of 500, the object will be painted with 14 pulses per scan at most.
Many countries such as Canada, UK and Australia, scan a large enough number of angles with their radars to have an almost continuous vertical view (taking into account the radar beam width) and produce CAPPIs. Other countries, like France and United States, use fewer angles and prefer PPIs or composite of maximum reflectivities above a point.
The resolution of any radar depends on the width of the beam and the range to the target. For example; a radar with 1 degree beam width and a target at 120 km (75 mi) range will show the target as 2 km (1.2 mi) wide. To produce a 1-degree beam at the most common frequencies, an antenna 1.5 kilometres (0.93 miles) wide is required.
Given an example antenna that generates a beam of 2 degrees width – fairly typical – a conical scanning radar might move the beam 1.5 degrees to one side of the centerline by offsetting the feed slightly. The resulting pattern, at any one instant in time, covers the midline of the antenna for about 0.5 degrees, and 1.5 degrees to the side.
The AN/TPS-43 is a ground-based, non-fixed (i.e.: transportable) search radar. [ n 1 ] [ 1 ] The entire system can be broken down and packed into two M35 trucks for road transport. An updated version replacing the original shaped reflector and organ-pipe scanner with a phased array antenna was originally known as the TPS-43E2, but emerged as a ...
Five definitions of the beam width are in common use: D4σ, 10/90 or 20/80 knife-edge, 1/e 2, FWHM, and D86. The beam width can be measured in units of length at a particular plane perpendicular to the beam axis, but it can also refer to the angular width, which is the angle subtended by the beam at the source.
TPY-2 radar in travelling configuration View from the back on a deployed TPY-2 radar. The AN/TPY-2 Surveillance Transportable Radar, also called the Forward Based X-Band Transportable (FBX-T) is a long-range, very high-altitude active digital antenna array [1] [2] X band surveillance radar designed to add a tier to existing missile and air defence systems.