[TowerTalk] Grounding Vertical Radials

[jimlux]

On 6/1/18 7:46 AM, Grant Saviers wrote:
> Dan,
> 
> Correct, I measured the currents and wanted to see the pattern 
> distortion that resulted, after reading concerns about current asymmetry.
> 
> Previously, I modeled very simplified towers northwest of the vertical 
> (3 towers) affect on the pattern and found they were acting as 
> reflectors and shifting the pattern about 1.2db to favor the southeast. 
> The radial current asymmetry is a 0.4db influence in the opposite 
> azimuth.  Luck.
> 
> Developing a model for the steel building 56' x 70' x 14' is easier now 
> with not yet tried tools in EZNEC 6.  However, how to model a Ufer 
> perimeter foundation as the ground is tbd for me.  Any advice?
>

I doubt you could adequately model a ground network (in the ground) 
using a tool like NEC (even NEC 4).  NEC assumes that the soil 
properties are uniform (with some stuff like "cliffs" available), and 
while NEC 4 will handle buried conductors, there's some fairly 
idiosyncratic things about it.

Modeling a steel building is easy - do it like a car or ship - as a grid 
of wires. The wire spacing/diameter should be chosen so that the 
circumference of the wire is comparable to the spacing. (i.e. spacing = 
2*pi*diameter) - big diameter wires are fine.

 From a "interaction with antennas" standpoint, I'd do some experiments 
with a "thinned grid" to see how much difference adding more wires makes.