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## Re: [TenTec] New and Improved Terminology

 To: "Discussion of Ten-Tec Equipment" Re: [TenTec] New and Improved Terminology "Paul Christensen" Discussion of Ten-Tec Equipment Sat, 8 Jan 2011 06:50:12 -0500 mailto:tentec@contesting.com>
 ```> http://www.karinya.net/g3txq/temp/ground_zones_2.png Steve, Do you know if the elevation chart would change much if instead of a ground-mounted 80m quarter-wave vertical, a half-wave vertical dipole was used ? The maximum current point would rise a quarter wave above the ground and the Fresnel geometry would seem to change, albeit slightly in relation to the horizontal distance. Paul, W9AC . ----- Original Message ----- From: "Steve Hunt" To: "Discussion of Ten-Tec Equipment" Sent: Friday, January 07, 2011 9:22 AM Subject: Re: [TenTec] New and Improved Terminology > Folk who have been following the discussion may be interested in this > chart: > > http://www.karinya.net/g3txq/temp/ground_zones_2.png > > It shows how the optimum take-off angle of an 80m quarter-wave vertical > mounted over Sandy Soil varies as the radius of an excellent ground > screen (Salt water) is gradually extended outwards. It was produced by > using the capability of EZNEC to have two different radial ground media, > as I described earlier. > > Please note that this is simply an exercise in determining how far from > the antenna, ground conditions affect the take-off angle; we're letting > EZNEC do the trig that we could otherwise easily do ourselves with some > simple maths. > > Notice that as the ground screen grows from zero to about 100ft - the > range in which we might typically install a ground radial system - the > take-off angle barely changes. At the other extreme, above 500ft we are > beyond the Fresnel Zone in which reflections are taking place, and there > are no more improvements to be had. All the "action" takes place between > 100ft and 500ft. > > Unfortunately, for many of us that's an area that might well be outside > our property boundary. Even if it is not, at that radius the areas are > so great that we would need to put down massive amounts of copper to > have any significant effect on the ground conductivity. Hence Rudy > Severn's comment: "Any practical ground system will not affect the > radiation angle or far-field pattern!" > > 73, > Steve G3TXQ > _______________________________________________ > TenTec mailing list > TenTec@contesting.com > http://lists.contesting.com/mailman/listinfo/tentec _______________________________________________ TenTec mailing list TenTec@contesting.com http://lists.contesting.com/mailman/listinfo/tentec ```
 Current Thread Re: [TenTec] New and Improved Terminology (NVIS origins), (continued) Re: [TenTec] New and Improved Terminology (NVIS origins), Stuart Rohre Re: [TenTec] New and Improved Terminology (NVIS origins), Stuart Rohre Re: [TenTec] New and Improved Terminology (NVIS origins), Steve Hunt Re: [TenTec] New and Improved Terminology, Stuart Rohre Re: [TenTec] New and Improved Terminology, Richards Re: [TenTec] New and Improved Terminology, Steve Hunt Re: [TenTec] New and Improved Terminology, Walt Amos Re: [TenTec] New and Improved Terminology, Steve Hunt Re: [TenTec] New and Improved Terminology, Rick - NJ0IP / DJ0IP Re: [TenTec] New and Improved Terminology, Steve Hunt Re: [TenTec] New and Improved Terminology, Paul Christensen <= Re: [TenTec] New and Improved Terminology, Steve Hunt Re: [TenTec] New and Improved Terminology (NVIS origins), Rick - NJ0IP / DJ0IP Re: [TenTec] New and Improved Terminology (NVIS origins), Rick - NJ0IP / DJ0IP Re: [TenTec] New and Improved Terminology (NVIS origins), Dr. Gerald N. Johnson Re: [TenTec] NEC, ground, grounds, and radials., Dr. Gerald N. Johnson Re: [TenTec] NEC, ground, grounds, and radials., Steve Hunt Re: [TenTec] NEC, ground, grounds, and radials., Dr. Gerald N. Johnson Re: [TenTec] NEC, ground, grounds, and radials., Steve Hunt Re: [TenTec] NEC, ground, grounds, and radials., Dr. Gerald N. Johnson Re: [TenTec] NEC, ground, grounds, and radials., Steve Hunt