Why don't you just try modeling it? I've used EZNEC+ in the past to
model various beverages and the general result has always looked
plausible. The effects of various lengths, termination values, etc
matches expectations. The cost of the prgram would be less than the
cost of the wire you're thinking of experimenting with.
Dave AB7E
On 2/3/2015 6:39 AM, Patrick Greenlee wrote:
Chuck, A very good point.
That is the essence of my interest in the effect of having some
parallel grounded conductors (5 strand barbed wire fence with steel
posts) a short (TBD) distance below the beverage antenna. I'm curious
to know if the fence would act similar to good conductivity dirt WRT
Beverage performance.
If not, then what if the antenna wire were mounted above 3 parallel
but horizontally spaced conductors looking for the beginnings of the
effect that would be achieved theoretically with our old friend the
infinite conductive plane over which we mount our verticals? Why 3?
Because it would be easy to put a strand of wire on either side of the
top strand of barbed wire using readily available inexpensive plastic
insulating arms made expressly for adding electric fence wire to a
fence built with T-posts. With a little more fussing I could attach 2
wires either side of the center wire giving a better approximation of
the infinite plane. One of our experts can maybe tell me if the
parallel grounded wires need to be tied together laterally or if that
would matter.
Patrick NJ5G
On 2/3/2015 7:00 AM, Chuck Dietz wrote:
Part of the problem with comparisons of low band receiving antennas
made in
various locations is that the composition of the ground under the
antenna
makes a huge difference.
Chuck W5PR
On Mon, Feb 2, 2015 at 8:22 PM, Roger (K8RI) on TT
<K8RI-on-TowerTalk@tm.net
wrote:
That's why I have the HB and Antenna HB on the same machine as the
mail.
Items, topics, and components are so much easier and faster to find
than
with hard print. Less than 10 keystrokes to find nearly any
specifics on a
topic. Course as some of my answers have shown, I'm too lazy to always
double check!
I can't say the computer is smaller, lighter, or cheaper at 60#, 23"H X
7.5"W X 20" D, running 8 64 bit cores/CPUs @ 4.1 GHz, & 16 GB of
RAM and
cost less than half our first color TV. OTOH the Internet has been
a POS
this past week, so I'm glad I had most of the data here. Still, with
posted links on mans news groups, they came up invalid (err 404)
even from
news sites and some ham pages were taking so long to load they timed
out.
I don't think I was getting more than a fraction of the 100 Mbs
service I
pay for.
Speaking of "pay for" and I think this is relevant to hams who
depend on
electricity... My electric use in the shop has been down this past
year and
on the equalized billing plan It almost doubled last month (with
less use)
I think I smell a rate increase a coming.
73
Roger (K8RI)
On 2/2/2015 2:14 PM, Jim Brown wrote:
On Mon,2/2/2015 10:05 AM, Don wrote:
First, I'm surprised there does not seem to be any published
measurements taken at a common test site of a Beverage at various
heights
and lengths (such as done with yagi's, and other antennas on test
ranges).
Why do you assume that nothing like this exists? Beverages have been
around for nearly a century, and it is quite likely that there's a
lot of
published work that you haven't looked for in scientific journals.
It's
also possible to model antennas like this and do your own study.
There's a
lot about Beverages (and other RX antennas) in the ON4UN book, and
in the
ARRL Antenna Book.
Email reflectors like this one should not be a substitute for
pulling out
the books and studying them. Many of us who post answers to
questions like
this have done that study, or done that modeling, or built those
antennas,
and are sharing what we've learned. As VE7RF has noted, optimum
height is a
function of wavelength. When a Beverage is higher than that, it
doesn't
stop working, like throwing a switch, it just becomes less
effective. My
550 ft Beverages, a full wavelength on 160M, at an average height
of 5-6
ft, are quite effective on 40M, and are still working on 20M! How do I
know? I run diversity with my K3 using the TX dipole at 125 ft into
the
main RX and the Beverage into the second RX.
73, Jim K9YC
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73
Roger (K8RI)
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