[TowerTalk] Radial Ends Buried???

[Dan Maguire]

Jim Brown wrote:
>>> About ten years ago, I did the experiment of modeling a pair of radials cut to a free-space resonance, starting with them as close as NEC2 would allow it, and raising them in small increments to several feet.

That sounds like a neat experiment and AutoEZ's "Resonate" button
makes it easy to automatically adjust the length of the radial pair
(modeled as a dipole) for resonance as the height above ground is
changed.

Using bare copper #12 wire, here is how the velocity factor changes as
the height is raised from 0.2" to 100" (~8.3 ft) at four different
frequencies.  This is with EZNEC's "Average" ground, conductivity =
0.005 S/m and dielectric constant (relative permittivity) = 13.

https://i.postimg.cc/76r7FHng/image.png

And this is with three different ground characteristics all at the
same frequency.

https://i.postimg.cc/BQ7FqcCZ/image.png

If you have AutoEZ and you'd like to play with the model file you can
download it from here:

https://ac6la.com/adhoc/VF_vs_Radial_Pair_Height.weq

Instructions for use are shown on the Variables sheet.  And if you
don't have AutoEZ but you *do* have Microsoft Excel (sorry, not Libre
Office or Open Office) you can use the free Demo version of AutoEZ
(https://ac6la.com/aepurchase.html) just by changing the number of
segments on the Wires sheet to 29.  You'll also need the free EZNEC v.
7.0 (https://eznec.com/).

Dan, AC6LA