M... "I was thinking maybe I can find some coax that will
fit tightly in copper pipe so that I could use a shield.
- - - Do you think that would help the null?"

Spacing - Copper Pipe Shielded Coax Cable Loop Antenna
http://groups.yahoo.com/group/Shortw...a/message/9878

Take a chunk of the Coax Cable and the Copper Pipe
and go down to a Home Depot, Lowes, ACE or OSH.

Find one or may be two sizes of Clear Plastic Tubing or
Clear Hose used for Refrigerators and Air Conditioners
that will fit around the Coax Cable and inside the Cooper
Pipe. Note - Do Not Use the Black and Colored Hoses.

As-an-Alternative - Take some Masking Tape {Plain Paper
Tape} [Do Not Use Silver Duct Tape] and Tape it around
the Coax Cable every Six Inches (6") to act as a "Spacer"
between the Coax Cable and the Copper Pipe.

# 1 - Having a 'uniform' "Spacing" between the Coax
Cable and the Copper Pipe will improve the Peak-and-Null
performance of the Loop Antenna.

# 2 - Plus having a 'uniform' "Spacing" between the
Coax Cable and the Copper Pipe will make the day-to-day
results from the Loop Antenna more consistent since
the Coax Cable will not be moving about inside the
Copper Pipe as the Loop Antenna is moved about in
Travel.

IMHO - "In Theory" -This is... Just Plain Common Sense }


hope this helps - iane ~ RHF