Re: Topband: Modeling "Ground" and losses

["Tom W8JI" <w8ji@w8ji.com>]

> That of course will tell you the antenna is fairly Low Z, in order to get
> the efficiency back to as high as possible I laid 130 x 0.4 wave radials.
> With this I know  that the effective series ground resistance in my case 
> is
> about a couple of ohms,   and the overall result is good.
> So the unfortunate reality for amateurs is the shorter the vertical is 
> from
> a quarter wave, Ideally the longer the radials need to be.
That may not be as cut and dry as it appears. Radials do have standing 
waves, and so the minimum impedance at the base will appear when the radial 
is somewhat less than 1/4 wave long.
Lowest base impedance caused by the radial system does not always translate 
into lowest loss, however, since there are standing waves on the wires. I've 
seen this a few times, in the most recent case on 40 meters where 15 ohms 
more base feedpoint resistance did not cause a decrease in field strength 
compared to a  35 ohm base impedance.
Ham radio has a multitude of wisdoms about antennas and radials, many or 
most conflict with other views.
My feeling on this is most disagreements come from meaningless measurements 
or comparisons that have built up over the years.
73 Tom 

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