Topband: Top band antenna

F3WT ars.f3wt at
Wed Sep 13 15:50:17 EDT 2006

Hi all,
Dear Armin,

1° 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  
Dimensions: ac:  ∼30M ; ab: ∼10M; top to base : ∼12M; ac is up  
∼ 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  
( 180° 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                                     \

b                                          c'

2° I am also considering replacing the loop by a fractal loop. ( see  or other via google).  
The mechanics is a challenge for top-band.

3° Another nice antenna is an helicoïdal 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  

Hope to have helped you a little.


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