Hi all,
Dear Armin,
1Â I made an 80M LP qso with a vertical Delta-loop "toploaded " with
a deep " "Lecher-feeder" short circuited" at the bottom d .
In addition, there is dipole a'bc', whose ends are cross-connected to
c-b ( a to c' and a' to c) in the horizontal plane . Those wires are
not drawn ( too cumbersome in an e-mail). Feed is feed at b with a
symetricall tuner.
In theory, can be fed anywhere, at a, b,c, but also d.
The whole thing is oriented north-south here, works well into VK/ZL
on LP , the americas as well as east-bound, not ok for North-South
though
Dimensions: ac: â30M ; ab: â10M; top to base : â12M; ac is up
â 10M . Point a is a chemney, c: a tree 10M up anc b is a roof
window at my shack. The thing radiates "broadside". If you manage to
tune at d ( with another tuner or an LC arrangement) such as top is
a short circuit, the thing radiates broadside on 40M as well. Well...
they actually are many radiation patterns one can achieve depending
on the feed-point , even " end-of-fire " lobes. Its worth simulating
with Roy Lewallen, W7EL, EZNEC.
It looks like an XJK antenna or a 40 years old W8JK antenna of
Dr. Kraus described in most Antennabooks. Ity is also better known
now as HB9CV . It is somehow similar to a 2-el-quad set-up as a
Swiss-quad or better a Quagy (Quad/yagi), well.. more generally a
"Loopagy", hi! where two elements are both fed at out of phase
( 180Â or other).
This antenna did also work on 160M , still with a coupler, but less
efficient than on 80M and 40M.
/I I\
/ I I \
/ I I \
/ I I \
/ I I \
/ I I \
/ I I \
/ I I \
/ I_I \
/ d \
/
\
a
c
_________________________________
a'
b c'
2Â I am also considering replacing the loop by a fractal loop. ( see
http://www.hbci.com/~wenonah/cfa/fractal.htm or other via google).
The mechanics is a challenge for top-band.
3Â Another nice antenna is an helicoÃdal vertical Cu-tape-wrapped on
a fiberpole top-loaded as well , already referred to in this reflector.
I experienced one on 80M successfully.
But I sort of specialized a little bit in loop antennas and prefer
them...
Hope to have helped you a little.
73.
Pierre.
F3WT.
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