Topband: Short radials?

Tom W8JI w8ji at w8ji.com
Thu Sep 27 23:07:12 EDT 2012


> I have no evidence that would lead me to  doubt the measurements of the
> other bands.
>
> 160 meters measurenent:
> 15 ohm base R
> 2 ohm radiation resistance
> 5 ohm cool loss
> 8 ohm ground loss (rounded to 10)
>
> This is the accepted procedure for measuring base referred ground loss, is
> it not?

I used to think ground resistance always meant something, then I learned it 
didn't. I gave an example with a 40 meter system I tested.

Ground systems, even with buried radials, have standing waves. Standing 
waves change the impedance along the wire.  It is possible to have a wide 
range of ground system contributed resistance at the base of the antenna for 
a given amount of loss.

Something is correct within what we will accept all the time, or it is not a 
reliable method.

I think N6RK or k6mhe found similar results, and I know my truck acts like 
much less resistance than actual losses indicate.

I think the ARRL Handbook or QST had something someplace where a fellow 
moved an 80 meter antenna to the center of a car and had 2 ohms ground loss. 
I thought, "Wow, I'll just park a car under my vertical. Not only will it be 
a good ground, I'll also have a status symbol as soon as a tree grows 
through the windows."

73 Tom 



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