Hi Steve -
With only 4 radials, I expect that a few more would improve efficiency
and reduce the feedpoint impedance. NN4T/WA4CTA and I both observed a
reduction in impedance as radials were added from 2 to 4 to 6 to 8. The
change from 6 to 8 was pretty small so this may indicate that more than 8
will not have much influence. Both of our 160M radial systems were
attached at the 15 foot level. Your attachment at 35 feet is probably
more efficient due to less coupling to ground. Raising the ends may help
some, I just don't have any data. It is probably easier to add another 4
sloping wires than to make them level at 35 ft!
Evidence is mounting that a large number of ground mounted radials is the
most efficient method. Ground radials provide both a current return path
AND improved ground reflection. Elevated radials only provide the return
current path and therefore once the impedance stops changing with the
addition of more radials, I believe there is little benefit to be gained
from adding more (elevated) radials.
My 160M GP has 6 elevated radials at 15 ft. It works well but does not
seem as competitive as a shunt fed tower I used in the mid 80's with 50
ground based radials 150 ft long. (Conditions this season have been
abysmal west of the Eastern Time Zone line until mid January and
competition is probably a lot greater this cycle with many more stations
on the band.)
My 80M GP has 10 radials at the 15 ft level and is quite competitive,
often equal (and on polar paths) better, than my 130 foot high dipoles!
To Europe, there appear to be horizontal nights and vertical nights. To
Asia (mornings) the GP is almost always best. It helps to have both.
My article was published in the June 1994 issue of QST pp. 44-45.
73, Tom - N4KG
On Sun, 02 Feb 1997 11:14:10 -0400 WF3T <steve.steltzer@paonline.com>
writes:
>Hi Tom,
> Glad to see your post and grab your email address, hi. I'm
>using your
>160 tower feed system and have a couple questions for you. I'm
>currently
>using 4 radials. Does it help to add 2 or 4 more? And what does that
>do to
>the feedpoint impedence? My radials slope down from 35 ft to about 12
>or 15
>ft. Will it help to raise the ends? Again, what will that do to
>feedpoint
>impedence?
> I appologize if this was covered in your article, but I've
>forgotten
>which issue it was in now, and you know what a chore it is to find
>something
>hunting through a couple dozen QST's.
> BTW, the system works pretty darn good as is, but like most of
>us, I'm
>always looking for a bit more, hi. And nice to work you in the 160
>tests.
>
>
>Thanks, 73!
> Steve
>- WF3T
>
>*\* steve.steltzer@paonline.com (WF3T) *\*
>*\* Harley Davidson Inc. *\*
>
>
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