Topband: poor antenna- big dx ?
Sat, 12 Feb 2000 11:27:37 -0400
Wolf, I would like to add a non technical spin to your wisdom on this subject,
especially after reflecting on our last 1.8 Mhz contact wherein you where as
loud as any European I have ever heard and we rag chewed for over 1/2 hour
with 599 both ways. Then came excruciating periods of agony calling several
European stations over the last month for hours without even a qrz. Repeated
cycles of the thrill of a dx reply and the agony of none even, when conditions
are good, is the way for the inverted V or low dipole advocate. (Last night I
called EA6SZ for about an hour without even a qrz or partial and he was
stringing midwest stations.) That is the reality of an inverted vee or low
dipole the tempting of consideration that you have an antenna that works well
because there are some times that it does. But they will always let you
down especially when you need to get a new one like my attempts last night with
EA6SZ led nowhere. The sinking feeling of a dx station that you would like to
work indicating he going QRT because nobody else is calling him is the price
the false security of a working top band antenna will bring you. It hurts
when XZ0A peaks only for a few minutes every day but you fail to get the
contact because of the false security created by a low dipole or inverted V.
Since hurricane Lenny I have only 400 watts and 65 feet of vertical height but
I can run beverages for 1000 feet in most directions. I am convinced that
*any* appreciable horizontal radiation is wasted power between 90 degrees and
60 degrees except for local contacts. Although it will provide good
communication over longer distances at times, it is not something that will
work well when your back is to the wall.
You can have a much better chance if you concentrate on things that will lower
the angle and improve the radiation efficiency. Elevated verticals, top
loading but not excessive top loading, a good coil and vacuum variable, large
diameter conductors on shunt feeds, all are a step in the right direction.
Whereas running wire for a inverted V all over the place, even though it will
appear that it works well, will let you down. It seems ironic but it will be
nearly 100 years since your countryman Heinrich Hertz and his Italian
counterpart Marconi came up with a way to radiate some RF for long distances
and there is not much available to the normal amateur station that can do much
Yet there are no absolutes for this week I was working EA3VY on SSB on 1.840
(It is fair to call him a big gun out of Europe) and he switched to a new
antenna from his normal array. His signal jumped from 5x5 to 5x9 each time he
switched. It was very impressive. So what was this new antenna? A
conventional corner fed delta loop with the center at 100 feet. The delta
loop fed this way is supposed to have a small but useful vertical component.
It was the rage a decade or so ago but other antennas seemed to have taken
over for the big guns. Oh, well, back to antenna testing. There must be
something out there that delivers a significant improvement over the
"primitive Marconi" similar to what the CFA claims. Can anyone help me?
P.S. Herb, a corner-fed Delta looks like a vertical but with directivity
and gain broadside to the loop...NOT a "small but useful vertical component".
Good antenna but you need at least a 90-100' support even if you squash and
tilt it...de W4ZV.
FAQ on WWW: http://www.contesting.com/topband.html
Administrative requests: topband-REQUEST@contesting.com