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Re: [TowerTalk] Not QUITE a tower

Subject: Re: [TowerTalk] Not QUITE a tower
From: David Gilbert <>
Date: Tue, 13 Oct 2009 16:22:50 -0700
List-post: <">>

I have to run an errand and can't check it now myself, but doesn't EZNEC 
allow you to define two different ground zones (radial distances from 
center)?  If so, you should be able to compare the results of a uniform 
saltwater ground to the results for your example.  If you haven't been 
able to check that out by the time I get back later this evening, I'll 
give it a try.

Dave   AB7E

Paul Christensen wrote:
> 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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