David,
> This was just added to the Canadian AIP:
>
> Glide path installations generate a radiated signal resulting in a
> normal glide path angle of 3deg (it can currently be anywhere from
> 2.5deg up to 3.5deg). The normal antenna pattern, of glide path
> installations, generates a side-lobe. The side-lobe pattern
> produces a false glide path angle at three times the set angle
> (e.g., at 9deg for a normal 3deg glide path angle).
>
> I've never been so high on an ILS that I've seen this, of course, but
> it's interesting, and should be an easy effect to model. Any
> volunteers?
Great idea, but I haven't got any time to help with this right
now... what I can say though is that I assume from the description
that the side lobes should also be somewhat (3 times?) less sensitive,
i.e. you need a larger angular deviation than normal to reach the same
needle position.
Your post raises another question of course: in FlightGear, the
glideslope and localizer either both have sufficient signal or none of
them. Is this realistic? I would have thought that the glideslope
signal is detectable from a wide range of directions but only in a
small vertical range, whereas the localizer is detectable at a variety
of altitudes and only in a narrow range of "radials". What's real ILS
like? (You must know by now... congrats BTW)
I'm asking because the glideslope lobe at 9deg would also have smaller
range due to the smaller emitted intensity. But currently the range
doesn't vary as long as the localizer is detected, which sounds a bit
funny to me.
Andras
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Major Andras
e-mail: [EMAIL PROTECTED]
www: http://andras.webhop.org/
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