ILS Localizer

28.10.2004

Submission:

I would like to pose several questions.

What is the minimum azimuth operationally required for ILS localizer service volume and why? What is the optimum service volume?

Background:

In siting an ILS localizer today, one of the most difficult problems is to have broad radiation to meet coverage requirements while having a site free from multi-path or signal reflections. Reflections from hangars and aircraft often arrive back onto the runway centreline to disturb the signal for an approaching aircraft. The nature of these reflections at a given airport can result in potentially large critical and sensitive area boundaries that reduce the overall efficiency of the airport and result in additional restrictions on construction on and around the airport that could bring local economic growth to a region. Many of these limitations are a result of the wide, +/- 35 degree, coverage requirements for the ILS localizer. ICAO says that +/- 10 degrees is the minimum that can be operationally accepted. Although ICAO states this, many believe it represents an operational deficiency and are reluctant to accept the reduced service volume. We are promoting a new standard of +/- 15 degrees of coverage. By reducing the azimuth coverage, a powerful breed of next generation ILS antennas can be built that will enhance airport efficiency and allow growth. What is sacrificed operationally from our proposal?

John H. Johnson SR. (President)

Watts Antenna Company (www.wattsantenna.com)