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Re: [TenTec] New and Improved Terminology (NVIS origins)

To: tentec@contesting.com
Subject: Re: [TenTec] New and Improved Terminology (NVIS origins)
From: Stuart Rohre <rohre@arlut.utexas.edu>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Thu, 06 Jan 2011 15:46:42 -0600
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
I think you could read Gordo's comments as intending to say there is 
more efficiency, and hence more signal power radiated at the optimum 
(low angle for a vertical), if you have a good near field ground.  The 
reflections off ground beyond the Fresnel Zone, (2 t0 5 wavelengths away 
from the antenna), are what control what low angle you achieve for the 
longer distances.  In other words, what is the ground condiiton well 
beyond your yard, where the first reflections happen from your antenna? 
  This is not to be confused with reflections that might happen in the 
near field because your ground mounted vertical might be lower than the 
surrounding surfaces, or close to other reflecting or blocking 
conductive surfaces.
It would help if Gord had been more precise, or given more explanation 
to avoid multiple interpretations.

At our local club, this week, we had a guy give the basics of Antennas 
from a point of view I have never seen expounded, but which is a good 
way of looking at the subject.  He defined an antenna as a capacitor, 
whose plates, (elements) are designed to be most inefficient at holding 
energy, and thus, efficient at "leaking" the radio wave to cause 
radiation.  An interesting way to look at it, and perhaps easier for 
some to comprehend.  Personally, I have liked John Kraus's approach of 
taking a coaxial feeder and opening up the center and shield to form a 
dipole.  When the two elements are at 180 degrees to each other, you had 
maximum antenna effect, if the elements were resonant.

A local also presented a show and tell on the Circular Polarizing phase 
shifter needed to use with two crossed dipoles.  The purpose based on 
the article on page 33 of Dec. 2010 QST, is to enhance your reception
of either circular polarization sense, since the article points out that 
all received signals are going to be elliptically, (a case of 
circularity) polarized upon ionosphere reflection.  Using a phased pair 
of crossed dipoles, you can favor the Ordinary Wave or the Xtraordinary 

-Stuart Rohre

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