[TowerTalk] Grounding Vertical Radials

[Grant Saviers]

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?

Grant KZ1W

PS any chance you are at SeaPac now?


On 6/1/2018 0:54 AM, Dan Maguire wrote:
> Grant wrote:
>>>> I modeled measured radial current asymmetry by putting a current source in each radial at the measured value ...
> Sounds like Grant wanted to see the pattern distortion caused by
> current asymmetry in the radials.  Another possibility would be to
> include the suspected *cause* of the asymmetry (such as a nearby
> tower) in the model and then look at the *modeled* currents in the
> radials.  To see the currents in the radials you can follow a
> suggestion given in the EZNEC Help under "About Sources":
>
> <quote>
> Using sources as ammeters or voltmeters
>
> A zero volt voltage source can be used as an ideal current meter to
> measure the current at any point in a wire, and a zero ampere current
> source can be used to measure the voltage across a small gap. A zero
> volt voltage source is effectively a short circuit so can be placed in
> a wire without disturbing normal operation. ...
> </quote>
>
> Using the very simple EZNEC sample model "Vhfgp.ez" as an example,
> here's what you would see after putting a "current meter" at the
> inboard end of each radial.
>
> https://postimg.cc/image/6koo9ohtn/
>
> As an alternative, for AutoEZ users you can look at the "Currents" tab
> of AutoEZ and place an "Info box" on any desired segment.  Like so.
>
> https://postimg.cc/image/4u5n7p057/
>
> Dan, AC6LA
> https://ac6la.com/
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