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VOR Navigation Antenna

Aviation & Air-Traffic-Control Antennas Navigation VHF Aviation

A ground beacon whose circular antenna array lets aircraft read their bearing from the station.

Band
VHF (108-118 MHz)
Gain
Low (omnidirectional by design)
Polarization
Horizontal

Photos

Real-world photo of a VOR Navigation Antenna in use
Real-world example. Source: Wikimedia Commons (CC BY 2.0; Sharon Hahn Darlin).

Radiation / wave patterns

New to these diagrams? How to read a radiation pattern →

Radiation pattern of the VOR Navigation Antenna
Ground station seen from above: it radiates in all directions; an aircraft reads its bearing from the signal's phase, not its strength.

How & why it works

A VHF Omnidirectional Range station tells an aircraft what radial (bearing) it is on. The ground antenna radiates one reference signal equally in all directions and a second signal whose phase rotates around the compass—classically by electronically spinning the pattern of a ring of antennas (a Doppler VOR uses a wide circle of elements switched in sequence to synthesize that rotation). The aircraft simply measures the phase difference between the steady reference and the rotating signal; that difference equals its bearing from the station, the same from any direction, which is why the ground array is circular and the coverage omnidirectional.

Real-world uses

En-route and terminal radio navigation; defining airways and approaches worldwide.