I can think of a reason to know if a tower is resonant because in the last
50 years it has happened to me several times.
Suppose you have a 70ft tower and an 80m full sized vertical. Where, or how
far away, do you put the vertical from the tower.?.?. Unless you put the
vertical more than 100ft away from the tower, the tower is going to act as a
reflector in some direction. Or even better if you have a 60ft tower then it
is going to give you gain in some direction. Or if you have 40m phased
verticals and you have a 60ft tower somewhere nearby, you are going to get
pattern distortion.
Just my -2cents worth
73
MAL
N7MAL
BULLHEAD CITY, AZ
http://www.n7mal.com
Everyone in the world is
entitled to be burdened
by my opinion
----- Original Message -----
From: jimlux
To: Rudy Severns
Cc: towertalk
Sent: Wednesday, February 11, 2009 4:52
Subject: Re: [TowerTalk] tower resonances
Rudy Severns wrote:
> I must apologize to the reflector for asking my original question in such
> a
> broad way when my interest is actually much narrower.
>
<snip>
> My question really should have been: are there other ways to determine
> tower
> resonances that do not require elegant instrumentation but actually work?
>
> Thanks and 73, Rudy N6LF
>
>
Let's turn the question around.. why would you want to know whether the
tower is resonant (unless you're actually using it as a radiator).
There's the idea that it might corrupt the pattern of an adjacent
antenna, but then, what you're really interested in is whether the
pattern is potentially corrupted.
When modeling antennas, I do things like model rain gutters etc to see
if they'll have an effect, but there, I'm not really looking for
accuracy in the model, but just to see if there's any current in the
potential parasite. If there isn't, then I assume it's not going to
affect the pattern much. But the model of the gutter is just a single
wire (i.e. if the wire has current, so will a big old steel gutter
nailed to the house).
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