Paul,
I have always built my horizontal loops as a square, one
wavelength long for the lowest frequency to be used and fed it in
one corner with 450-Ohm Ladderline openwire. I generally tried
to have the feedpoint in the southeast such that the corner
opposite the feedline was pointing towards stateside. This seems
to be the strongest lobe on 20m.
Occasionally I used the loops on half the design frequency (e.g.,
80m loop on 160m).
To enable that, I simply opened the loop at the corner opposite
the feedpoint.
I usually matched the loops with a home-brew matchbox based on
the "Annecke" design which is an improvement over the original
Johnson Viking KW matchbox (additional, 3rd variable cap in the
TX side). For QRP work, I used a Z-match and sometimes simply
old matchbox and a 4:1 current balun.
An interesting variant for us here in Europe with sub-postage
stamp sized lots is to put up the 40m version - it can be as low
as 5m (15') and still work effectively. Then add the ability to
remotely open the far corner of the loop and you get a good 80m
antenna as well.
My vertical loops were completely different - triangular, as I
described in an earlier post, and fed just beside one of the
lower corners with an electrical quarter wavelength of 70 Ohm and
then random 50 Ohm coax. These are DX-only antennas.
73
Rick
>>>>Getting back to loops, with apologies for the TT list
hijacking, I wonder
how and where you are all feeding / did feed your loops?
Co-ax, balanced feeder, impedance of feeder, location of
feedpoint?
Need for balun / RF choke etc?
Shape of loop?
Any good web sites or references? ( I have read lots of LB Cebik
W4RNL's
material )
Should you wish to mail off list to spare peoples' inboxes, a
valid email
address for me is
gw7lhiAThotmail.com obviously, replace AT with @ OK!
An interesting discussion, even if not strictly TT oriented.
Paul MW0CDO.
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|