Thanks to ZS6EZ for the excellent recount of the "battle Creek" special.
The antenna is a modification of the "Minooka" Special detailed starting on
page 15 of QST, December 1974. The article aws re-printed in the ARRL
Antenna Anthology, 1978 (but now out of print). The guys (W8UVZ, W0CD,
K8GG) do an excellent job.
the article was one of the first to really target building an efficient 160
meter antenna and there is even a mobile version. Page 16 of the QSR
article (called fig 1) is an excellent illustration of vertically polarized
antennas. Fig 2 on page 18 shows other antennas that prove effective for
Dxing. The antenna at the top right (submitted by K8RRH) is actually the
famous half quad or grounded U. K4TEA has used this successfully after it
was installed by Dave Fischer W0MHS (now W7FB). Dave is better know as
"Loop Skywire". The Grounded U is for home antenna use and is not a portable
vertical.
I called K8RRH and spoke with him at length about the flat top portion of
his antenna. Turns out he loaded the top to 1/4 wavelength with a cage and
said that 130' was the true flat top. K4UEE and I quickly put up the
grounded U and found that K4TEA's worked great because his was out in the
open. Ours ran over the house and was connected to the tower in the center
so it worked great in one direction or the other but the tower/house did the
antenna in. The actual antenna is 130' flat top and 65 to 70' down at each
end. Use as many radials as you can at each end, feed one end with coax or
hardline, and add a tie back line (a ground radial between each end that
ties the grounds together) that Dave recommended... Pattern is oval with
slight favor to direction (endfire) of the down wire that is fed. Works
great on 80, too (actually is a great all band antenna). Another was
installed at N4HOH and used as the multiplier antenna in a M/S
effort..worked better on 20 that most tri-banders! Here the antenna was
installed with one vertical leg only 9' from a 100' Rohn 25. The other side
was in a tall pine. We only had a couple or radials but it worked pretty well.
Never too late to get those low band antennas ready for the "season" on 160!
Dave K4JRB
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|