The Localizer

The localizer subsystem radiates a signal from the ground providing azimuth (lateral) guidance for a landing aircraft. The signal is transmitted to a visual display on the aircrafts VOR-LOC receiver, to assist the aircraft in easily finding the runway centerline. The ground-to-aircraft signal depicts the aircraft's approach position relative to the runway centerline.

When the aircraft strays to the right or left of extended centerline of the runway while on approach, the pilots cockpit display will indicate that the pilot, or the autopilot, must take the proper correction to allow landing safely.

The localizer antenna uses Log Periodic Dipole (LPD) radiating elements, and is available in several configurations. It is normally located on an extended centerline 92 to 610 meters 330 to 2000 feet off the stop end of the runway. A compact, environmentally controlled shelter is located 250 feet from the antenna and houses the localizer electronics, allowing technicians to work comfortably and protecting the system from the elements.

Electrical/Hardware Details

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The Localizer component operates on one assigned frequency in the range of 108.0 to 112.0 MHz and is compatible with standard VOR-LOC avionics.

The narrow beam wide aperture capture effect array, Thales ATM’s development, solves localizer performance problems due to reflections, at even the most difficult sites. Several localizer antennas are available all of which use Log Periodic Dipole (LPD) radiating elements. The eight element narrow aperture LPD is supplied as the standard localizer antenna. If siting becomes a factor, the eight element narrow aperture array can easily be expanded to a wide aperture fourteen element array. Thales ATM will survey your site to determine which system is needed.

The 14 element LPD may also be driven by a two frequency (capture effect) transmitter to even further increase directivity where needed to overcome the most severe siting limitations.

The LPD antenna system is complete with supporting structures, obstruction lights, all necessary cables, distribution and integral monitoring networks. The radiating elements are frequency-independent horizontally-polarized dipole radiators. This provides an antenna that is highly directional in both planes, has a low profile 2.13 meters (7 feet) tall which may be installed closer to the runway stop-end.

The LPD incorporates integral monitoring which means greater reliability of the antenna over a wide range of environmental conditions.

The LPD is impervious to ice and snow build-up and no degradation in the radiated signal is seen under the most adverse conditions. This means that radomes and antenna heaters are not needed.

 

 

 

 

 

The LPD is easy to install and maintain, frangible and has a proven performance under extreme conditions.