This topic made me curious to see what was on Google Maps:
http://maps.google.com/maps?q=40%C2%B02'57%22N+88%C2%B022'50%22W&ie=UTF8&ll=40.049563,-88.380675&spn=0.01636,0.038409&hnear=0x880ccc1bf72e2559:0x257eb5f56359d600,%2B40%C2%B0+2'+56.91%22,+-88%C2%B0+23'+15.98%22&gl=us&t=h&z=15
(may have to do some cut and pasting of the link.
Looks like not much left although the "circle" is still well defined for
some reason.
On 2/5/2013 8:35 PM, Gary K9GS wrote:
Or there's this one in Champaign, IL at the University of Illinois.
http://www.ece.illinois.edu/about/history/wullenweber/index.asp
It's been several decades since I've been out there and up close. In the
early 80s it was already in considerable dis-repair.
On 2/4/2013 12:53 PM, donovanf@starpower.net wrote:
Hi Lee,
You can save yourself lots of engineering effort if you simply make
yourself a copy of this one:
https://maps.google.com/maps?q=40+43+24+n,+141+19+44+e&hl=en&ll=40.72308,141.328892&spn=0.003313,0.006968&sll=40.723876,141.329155&sspn=0.026507,0.055747&t=k&z=18
My former employer (then Sylvania, now General Dynamics Advanced
Information Systems) installed it in 1966 at Misawa Air Base, Japan.
I believe its still exists, but its probably no longer in use due to
technical obsolesence, high maintenance costs and unavailability of
spare parts. An identical array installed at Elmendorf Air Base,
Alaska is also still in existence as far as I know. Maybe you can
purchase one of them!
Many copies of the original 40 element German "Wullenwever" array were
built all over USSR shortly after World War II, some may still exist.
Among other things, they tracked the 10 and 20 MHz Sputnik beacons
that some of us recall.
73
Frank
W3LPL
---- Original message ----
Date: Mon, 4 Feb 2013 10:13:55 -0800
From: "Lee K7TJR" <k7tjr@msn.com>
Subject: New 160M high performance receiving antenna at W3LPL
To: "Robert McGwier" <rwmcgwier@gmail.com>, "Frank Donovan"
<donovanf@starpower.net>
Cc: "Topband" <topband@contesting.com>
Hello Bob and all, Yes I agree on the issue of needing the
stable impedance
from the elements to drive the passive systems. I still have
some questions
in my mind about the radials and here is why. I have made
many field tests
where I measured the actual phase and amplitude differences
between two
receiving elements where one is held constant and parameters
around the
other were changed such as ground rods, radials, and such.
Both were
receiving signal from an equidistant transmitted source.
What I can tell you
for sure about this is that with a Hi-Z system the phase and
amplitude shifts
become quite unstable when radials are used. I do not know
this to be a
fact with loaded elements but I have seen evidence of some
received
signal shift due to the presence of the radials to the
element. This test really
opened my eyes about received signals and what objects might
affect
them. I have plans to buy the NEC4 engine and do some more
field tests
using another technology that should give me more answers. It
is these
minute details that prevent us from making these RX antennas
even smaller.
There is no doubt that the state of the art is advancing in
receiving antenas
with all the work that is and has gone on. I am confident
that what we are
presently doing is not perfect and I expect the state of the
art still has a ways
to go. There have been many man years of work by many people.
I hesitate
to name calls but a few notables are K6SE, W7IUV, W8JI, K9AY,
W3LPL,
W5ZN, W1FV, NX4D, N4IS, AA7J, K1LT and many many others that
I
apologize for not having the space here or personal memory at
the moment
to mention. There are more man years of work to do.
I still covet the 96 element Wullenwever antenna invented
around 1940!
Lee K7TJR
>The issue is getting sufficient ground radials so that
changing soil conditions: dry season, wet season, etc have
minimal impact on the impedance which is the easiest
measurement of the changing conditions. Joel and I did
measurements several times and when he was near drought he
found he had to add radials to stabilize the performance.
Once done, his system has been stable since.
Great news on both of you successfully deploying.
Bob
>N4HY
_________________
Topband Reflector
--
73,
Gary K9GS
Greater Milwaukee DX Association: http://www.gmdxa.org
Society of Midwest Contesters: http://www.w9smc.com
CW Ops #1032 http://www.cwops.org
************************************************
_________________
Topband Reflector
|