[Antennas] Antennas Digest, Vol 86, Issue 1

Wed Mar 2 08:46:27 EST 2011

I would disagree with the "been around 50 years" comment. Been a ham here
since 1976, never owned a commercial antenna, and have studied antennas the
entire time. There have been few references to double coax, and that was
often 50 ohm where it connected with open feeders or twinlead as a
passthrough need. The doubled 75 ohm coax concept is not "common." And
unless the vertical is actually elevated, the radials don't need to be
"tuned." There just needs to be as many of them as you can make work with
your installation if ground mounted.
Counterpoise gets tuned, radial don't need to be.
Mike, k5wmg
Pipe Creek, Texas
A thousand words a day. Five days a week. For life.
On Wed, Mar 2, 2011 at 7:38 AM, Ron Youvan <ka4inm at tampabay.rr.com> wrote:
> Henry oz3o n2nr Mei'l's wrote:
>> > I experienced that immediately after (April!) rains showers, I could
> work
> > Florida and other Southern states on 40 meters AM from NYC, in mid
> > afternoon, running about 70 Watts -- the antenna was a 1/4 vertical using
> a
> > wire mesh fence as ground counterpoise.
> > I could not do this in dry weather. Sunspot activity was also very
> favorable
> > in the late 50's.
>> Much more counterpoise (tuned as in 1/4 wl) and you can enjoy that
> performance year round and more.
>> > Since the theoretical impedance of an ideal GP is 35 ohms, what about
> using
> > two parallel 70 ohm
> > cables? But I suppose 50 ohms approaches the actual impedance of
> non-ideal
> > GP's. By adjusting the angle of the radials
> > with respect to the horizontal, 50 ohms can be achieved, assuming your
> feed
> > point height and physical environment makes this a practical possibility
> --
> > not often the case on the lower bands.
>> Two 75 Ohm cables (the exact same length) in parallel is perfect and
> has been used for at least 50 years. (RG-59, RG-11 or cable company wire)
> --
> Ron KA4INM - Endless Loop: n. see Loop, Endless.
> Loop, Endless: n. see Endless Loop.
> -- Random Shack Data Processing Dictionary
>> ______________________________________________________________
> Antennas mailing list
> Home: http://mailman.qth.net/mailman/listinfo/antennas
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Antennas at mailman.qth.net
>> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>