[TowerTalk] Re: [Antennas] unusual vertical installation problem

[Jim Reid]

Hi Warren,

My opinion, for whatever it might be worth (not much!):

1.  I suspect that the performance up on the platform will
not be noticeably different from that realized now with
the two whips Ned has been using somewhere lower
on the forward part of the ship.  Why no difference?

Because a vertical is a vertical,  and being higher up does
not change the take off angle from a vertical,  unless
it is raised at least a good wave length fraction away
from what ever is forming the effective ground plane.
Sounds as if there is enough metal up high that the
vertical would not be able to tell a difference from
the conditions of the two whips somewhere lower on
the ship now being used.  Now there may be some
difference from reflections caused by metal objects
at the same level as the two present whips,  and
similar changes will occur when those rotating radar
dishes are installed up beside the proposed new
vertical antenna site.  Suppose how quickly metal
falls away below the platform as compared to
metal around the two present whips being used
in parallel,  as I understand the situation described
by Ned when on KH6BB.

And I sure agree,  the use of a tuner will be needed.
As I also understand,  you want to use existing coax
cable which runs already from the "radio room" up to
the proposed high platform.  I gather it is pretty good
sized coax as well.  So no need to bother with a
remote tuner,  just use one in the radio room;  that
oversized coax will handle whatever vswr will be
on the coax line caused by antenna Z,  coax Z
mismatch.  This will be true whenever/if you ever
add an amplifier to the older radios now on board
which were provided by the Navy League.

All of the above is just maybe,  hi.  I have no way of
really knowing.

73,  Jim,  KH7M



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