The Probert Encyclopaedia of Science & Technology

LOCALIZER

A localizer is a form of radio beacon used in instrument landing systems for aircraft. It is located about 230 meters beyond the stop end of an airfield runway and radiates two signals of different frequencies from two aerials whose polar diagrams overlap in such a way that their signals are of equal strength along the centre of the runway. In the receiving equipment fitted in the aircraft the two signals are applied to a centre-zero instrument. When the indicating pointer of the instrument is in the centre (zero) position the pilot knows that he is correctly aligned with the runway.
Research Localizer