> resistance. In actual use the feedpoint resistance will be
> higher. The difference is
> due to losses. The radiation efficiency is then
> calculated. As the GND system
> is improved the base resistance will decrease. I use this
> method and it is
> convenient. It has confirmed simulations and articles that
> say that many short
> radials is not much better than a few short radials.
I measured dozens of systems and that method will not work
except by pure luck.
As an example just a few moths ago Roy Lewallen and I
measured a series of 40 meter vertical radial system. We had
a very low base impedance with four elevated radials (about
40 ohms) but about 16 buried radials produced identical FS
with a base impedance of about 60 ohms.
I've found the same to be true when measuring FS on 160 and
80 meters, as well as the BC band.
I also think Rudy Severns posted something on here a month
or two ago agreeing with this.
If you want to know FS change you really have to measure
the FS.
73 Tom
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