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#1
May 28th 04, 01:15 AM
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The longer runways are more likely to have critical areas.
Why? Jose -- (for Email, make the obvious changes in my address) 
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#2
May 28th 04, 02:17 AM
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Teacherjh wrote:
The longer runways are more likely to have critical areas. Why? The localizer will be closer to the (opposite) runway threshold. All the best, David
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#3
May 28th 04, 02:24 AM
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In article
ogers.com, David Megginson wrote: Teacherjh wrote: The longer runways are more likely to have critical areas. Why? The localizer will be closer to the (opposite) runway threshold. All the best, David Why should runway length affect how far the localizer antenna is from the runway end? Localizers are designed to have a fixed width (something like 700 ft lateral displacement for full-scale deflection on the CDI) at the arrival threshold, so longer runways will have narrower angular beam widths. But (to the best of my knowledge) this is done by adjusting the spacing of the transmitting elements on the localizer array, not by adjusting the distance of the array from the runway end.
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#4
May 28th 04, 02:34 AM
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Localizers are designed to have a fixed width (something like 700 ft lateral displacement for full-scale deflection on the CDI) at the arrival threshold, so longer runways will have narrower angular beam widths. Doesn't make sense to me. Angular beam width should be constant - for the far field. Then the antenna is placed at the distance from the arrival end (also constant) that gives the proper width. No? Jose -- (for Email, make the obvious changes in my address)
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#5
May 28th 04, 02:02 PM
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"David Megginson" wrote in message le.rogers.com... The localizer will be closer to the (opposite) runway threshold. So what?
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#6
May 28th 04, 03:01 AM
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"Teacherjh" wrote in message ... The longer runways are more likely to have critical areas. Why? Because the localizer spreads out at a constant rate. The longer the runway the wider it will be at the end of the runway.
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#7
May 28th 04, 12:33 PM
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"Newps" wrote in message ... Because the localizer spreads out at a constant rate. The longer the runway the wider it will be at the end of the runway. But the localizer critical area doesn't extend to the end of the runway. For a category I ILS it typically extends only 2000 feet from the antenna array.
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