Over many years I have tried several antennas for 160 meters. The best one
so far is a very odd shaped
full wave length 160 meter loop. I have been able to work JA's, UA0's, all
50 States with only 70 watts so it is radiating.
Half of the loop is in the vertical plane, and the balance runs along my
back yard wooden fence,
so half of the antenna is horizontal. EZNEC indicates the antenna is
basically vertically polarized. I assumed that because it is
a closed loop it is a balanced antenna, or is it really un-balanced because
of the shape? Being I think it is a balanced ant. I have
a current balun between my antenna tuner and my xmtr. (in effect the
antenna tuner is floating above ground because of the current balun.)
The Xmtr is grounded via a # 6 ground wire to a 10 foot ground rod located
directly outside of my
ham shack. Distance from xmtr to gnd rod = 28 inches.
I have laid a few radials where I could fit them in the available space in
my yard.
My questions is, what do I attach the radials to? Should I attach the
radials to the ground rod, or to the antenna
tuner chassic? Remember there is a current balun between the tuner and
xmtr.
Modeling the loop in EZNEC indicates that if I add a small number of radials
(20 radials, 1/8 wavelength long,) at the feed point
the gain actually drops by about 1.5 db? I live on a odd shaped small city
and very little room for radials. My surrounding soil conditions
are poor being I am located on the southern slop of a mountain, clay and
rocks. Th ground is wet though because we get a lot of rain, 80
inches a year or more.
There seems to be many opinions in regards to what I should do. Some have
strongly recommended that I don't
attach any radials to the station ground but didn't provide me with the
reason why???. Maybe someone can shed some light on this subject.
By the way, I recently built a rotatable Diamond Shaped Terminated Loop
which has improved my listening ability on
160 significantly. I have posted a page describing this experience and on
the the web page is a dow-loadable copy of my EZNEC
file for my xmting antenna.
Here is the URL to my site:
http://www.shelbrook.com/~ve7ca/Ant160.htm<http://www.shelbrook.com/%7Eve7ca/Ant160.htm>
--
Markus Hansen
VE7CA, North Vancouver, BC CANADA
Web site: http://www.shelbrook.com/~ve7ca/<http://www.shelbrook.com/%7Eve7ca/>
_______________________________________________
Topband mailing list
Topband@contesting.com
http://lists.contesting.com/mailman/listinfo/topband
|