Definition
A ground-based radar antenna that physically rotates to sweep its beam through 360 degrees, detecting aircraft by transmitting radio energy and receiving the reflected return as it turns. Rotating radar antennas are the traditional surveillance method used by air traffic control and are referenced as the older technology that ADS-B is designed to supplement or replace.
Plain English
A radar dish on the ground that spins around in circles, sending out radio signals and listening for the bounce-back to figure out where airplanes are.
Context Anchor
Seen in discussions comparing traditional radar surveillance with Automatic Dependent Surveillance-Broadcast systems.
Derivation
Radar comes from 'RAdio Detection And Ranging,' coined in the 1940s. The antenna rotates so its narrow beam can cover the full sky around the site rather than pointing in just one direction.
Why Pilots Care
Understanding this term clarifies why conventional radar has range and update limitations that ADS-B was designed to overcome.
Analogy
Think of a lighthouse beam slowly sweeping across the sea. A ship is only lit up briefly each time the beam passes. A rotating radar antenna works the same way—it only 'sees' an aircraft when its beam sweeps across it.
Grounding Statement
Picture a radar dish turning steadily, checking one slice of sky at a time as it goes around.
Intuition Check
Do not picture any antenna that happens to spin on an airplane. In this context, rotating radar antenna means the scanning antenna used by a radar system, usually at a ground radar site.
Example Sentence 1
Unlike a rotating radar antenna that updates a target's position only once per sweep, ADS-B provides position information about once per second.
Example Sentence 2
Unlike ADS-B, which broadcasts GPS data, traditional radar depends on a rotating radar antenna to locate traffic.