Plain English Meaning
An antenna that 'points' — it sends or picks up radio signals best in one chosen direction, and weakly in others.
Full Definition
An antenna designed to transmit or receive radio signals more strongly in one direction than in others. Its radiation pattern is shaped so that signal strength is concentrated along a preferred bearing, allowing the antenna to favor signals coming from (or going to) a specific direction while reducing sensitivity to signals from other directions.
Context Anchor
Seen in aircraft radio, navigation, and ground-station equipment discussions where signal direction or signal strength matters.
Derivation
From 'direction' (Latin directio, meaning a straight course or aiming) plus 'antenna.' The name simply tells you what the antenna does: it works in a particular direction rather than equally all around.
Why Pilots Care
Provides stronger, more reliable signals for navigation and communication while reducing unwanted interference from other directions.
Analogy
Think of a flashlight versus a bare bulb. A bare bulb (non-directional antenna) lights the whole room evenly. A flashlight (directional antenna) sends most of its light one way, so it's much brighter in that direction and dim everywhere else.
Intuition Check
Do not assume a directional antenna automatically tells you the aircraft's direction. It means the antenna's signal is stronger in certain directions than in others.
Example Sentence 1
The ADF uses a directional antenna so the needle can point toward the selected NDB station.
Example Sentence 2
Maintenance replaced the omnidirectional antenna with a directional model to strengthen the signal on the primary comm radio.