Definition
Radar antennas that steer their beam by electronically shifting the phase of signals across a fixed array of small radiating elements, rather than by physically rotating or tilting a dish. Because there are no moving parts to swing the beam, the radar can point in a new direction almost instantly and can update each aircraft's position many times per second.
Plain English
A radar that aims itself electronically instead of by spinning a dish, so it can look at many aircraft very quickly and refresh their positions much faster than older radars.
Context Anchor
Seen in PRM radar discussions for monitoring aircraft on closely spaced parallel approaches.
Derivation
From 'electronic' (using electrical signals rather than mechanical motion) and 'scan' (to sweep across an area looking for something). The antenna 'scans' its beam across the sky electronically — by timing signals across many small elements — instead of physically sweeping a dish around.
Why Pilots Care
They enable rapid, continuous tracking of aircraft during simultaneous approaches, allowing controllers to detect and resolve blunders before separation is lost.
Grounding Statement
The key idea is that the radar can look back and forth across the approach paths quickly because the beam is steered electronically, not by waiting for a moving antenna to turn.
Intuition Check
“Scanned” does not mean a person is visually looking around. Here it means the radar beam is being directed across an area to check aircraft positions.
Example Sentence 1
The PRM system uses electronically-scanned antennas to update aircraft positions roughly every half second, far faster than a conventional rotating radar.
Example Sentence 2
Because the antennas are electronically scanned, the radar can switch focus between two parallel runways without any mechanical delay.