On 8/16/2011 9:25 AM, Jeff Liebermann wrote:
On Tue, 16 Aug 2011 11:21:20 +0200, Helmut [email protected] ---
-.dotat wrote:

Thank you for the links, appreciate your help.

Y'er welcome. However, I still don't have a clue what you're trying
to accomplish. If you want super front to back ratio for a direction
finding antenna, you need a wall, not a phased single wire reflector
as in a yagi. Something like a dish or a panel reflector will work,
but is probably not practical. As you discovered, the position of the
reflector is very critical for maintaining the best F/B ratio. It's
also very sensitive to frequency. You might be able to make it work
with a flimsy tape measure, but it probably won't be very stable in
the field.

Permit me to offer another idea. Instead of direction finding by the
peak signal, do it with a null.

Exactly.. you can get very sharp nulls pretty easily. For simple
antennas, there's usually an ambiguity, but you can resolve that by
other means.