I seem to recall an indepth analysis on the AntennEx site showing that it
was the shield on the coax that did the majority of the radiating. A simple
proof would be to change the coaxial feeder length or how it is physically
run and look for VSWR changes.

Dale W4OP

Originally where I had the 40 Meter Isotron located I was using about a
50' coax run (RF-9913). I the moved the antenna to a different position
and had to add about 25' more of coax. The additional coax caused SWR
to jump from about 1.2:1 to 1.4:1. A quick returning of the "tuning
rod" on the antenna brought it back to 1.2:1

Last night I was doing more playing with the 10/15/20 combo, was able
to get the 20 meter size down to 1.2:1 and had about a 300 KHz bandwith
to say under 2:1 SWR so I'm happy with that. But still can't get the 10
& 15 meters to do any better than 3:1. It possibly might be the
location of the ant as its pretty close to some electical house wiring?

George