Hi Pete,
Actually, the answer is a little of both. For mutual coupling to
ground and what that does to element tuning and SWR, the antenna
will think its at about 60 feet (assuming it is otherwise pretty
much in the clear at that height).
For far field elevation pattern, unless the building is extremely
large, the height will appear to be the actual height above local
ground. There will be some effect. But as I said, unless the
building roof surface area is extremely large, the effect will be
amostly confined to very high elevation angles.
73, Eric N7CL
>From: brunet@us.ibm.com
To: <towertalk@contesting.com>
>Date: Thu, 7 Jan 1999 16:09:02 -0600
>
>We might get a chance to put a KT34XA on top of an existing 60'
>tower on top of an industrial building. I believe the roof is
>metal under the top layer of roofing material and I believe the
>tower is centrally located on this building so I assume this is a
>large ground plane under the tower. Can I assume the radiation
>pattern look like that of a 60' tower?
>Thanks, Pete
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