I would not be too concerned about groundwave above 160 m. I may be
mistaken about this but I believe groundwave is primarily a medium wave and
lower phenomenon. Above 3 MHz it begins to sharply fall off, even if you
have a lot of radials (which lower the angle of your skywave) and becomes
all about skywave and line of sight up higher. In other words, if you want
to get people close in on 80, your low horiz. loop will go straight up and
come down and blanket everything within a few hundred miles which no
groundwave on 80 could ever do. If you want that same coverage in the
daytime go to 40 meters.
You may be having rfi problems with the twinlead because you are not using a
balanced transmatch. the one you have is really designed for unbalanced
feedlines and is not tuning your twinlead in a way that keeps the sides
balanced, so they are radiating. Also it should be up off the ground and
away at least 4 or 5 inches from metal and be without sharp 90 degree bends.
Read this: http://www.somis.org/bbat.html
Commercially available version: http://www.palstar.com/palmain.htm
If you have access to QST magazine read this:
A Balanced, Everyday Approach to All-Band Bliss (238,675 bytes, PDF file)
QST April 2002, pp. 47-50
A noise free loop antenna system
http://www.arrl.org/members-only/tis/info/pdf/0204047.pdf
73,
Rob Atkinson
K5UJ
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