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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