Passive electronically scanned array: Difference between revisions

Revision as of 00:30, 19 January 2017

Revision as of 00:32, 19 January 2017

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[[File:DN-ST-92-02246.JPEG|thumb|The [[Mikoyan MiG-31]] combat aircraft with nose fairing removed, showing its [[Zaslon]] passive electronically scanned array radar antenna. ]]

[[File:Phased array animation with arrow 10 frames10frames 371x400px 100ms.gif|thumb|upright=1.2|Animation showing how a passive electronically scanned array works. It consists of an array of antenna elements ''(A)'' powered by a single [[transmitter]] ''(TX)''. The feed current for each antenna passes through a [[phase shifter]] ''(φ)'' controlled by a computer ''(C)''. The moving red lines show the wavefronts of the radio waves emitted by each element. The individual wavefronts are spherical, but they combine ([[superposition|superpose]]) in front of the antenna to create a [[plane wave]], a beam of radio waves travelling in a specific direction. The phase shifters delay the radio waves progressively going up the line so each antenna emits its wavefront later than the one below it. This causes the resulting plane wave to be directed at an angle to the antenna. The velocity of the radio waves is shown slowed down enormously.]]

A '''passive electronically scanned array''' (PESA), also known as '''passive phased array''', is a [[phased array]] antenna, that is an antenna in which the beam of radio waves can be electronically steered to point in different directions, in which all the antenna elements are connected to a single [[transmitter]] (such as a [[magnetron]], a [[klystron]] or a [[travelling wave tube]]) and/or [[radio receiver|receiver]]. This contrasts with an [[active electronically scanned array]] (AESA) antenna, which has a separate [[transmitter]] and/or [[radio receiver|receiver]] unit for each antenna element, all controlled by a computer. AESA is a more advanced, sophisticated versatile second-generation version of the original PESA phased array technology.