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Re: [TowerTalk] Not QUITE a tower

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Subject: Re: [TowerTalk] Not QUITE a tower
From: "Paul Christensen" <>
Date: Tue, 13 Oct 2009 19:05:56 -0400
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> Any idea how close to salt water a vertical dipole array has to be
> to work well?  15-20 ft to the side and 5 ft up close enough?

It's an interesting subject.  See "Lesson  #7" in the first link below for 
some guidance.

The other question I have not found conclusive answers to is "how much 
distance of saltwater is needed to establish the desired low take-off angle 
(TOA)?"  The intermediate and long-distance conductivity and geography 
fields set up the TOA.  But how much body of saltwater is needed to get the 
TOA of a vertical down to 1 or 2 degrees of elevation?

For example, consider placement of a 20m vertical dipole at a QTH located at 
the southern edge of a saltwater bay in the U.S. (e.g., Tampa Bay).  Let's 
say the bay's distance from the QTH to the northern edge of the bay is 5 km 
on a zero degree bearing.  North of the bay's edge, soil extends 
indefinitely.  From that QTH, can one expect a near zero degree TOA into 
deep Asia on short-path?   At some point, diminishing returns sets in once 
the TOA is established and no further separation of saltwater makes a 
difference.  It would be nice to have a formula that computes that final 
distance as a function of operating wavelength.

Paul, W9AC


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