Bobtail Curtain Question
 

If one were to use aluminum tubing for the vertical elements on a bobtail
curtain what would that do to the bandwidth and lengths of the elements as
compared to a all wire curtain? I would like to use 2 inch
tubing supported at the bottoms with a wooden post. I guess I might
want to put extra insulation on the pipes since there would be a lot of
voltage there ...


Doug N4IJ

"DOUGLAS SNOWDEN" wrote in message
...
If one were to use aluminum tubing for the vertical elements on a bobtail
curtain what would that do to the bandwidth and lengths of the elements as
compared to a all wire curtain? I would like to use 2 inch
tubing supported at the bottoms with a wooden post. I guess I might
want to put extra insulation on the pipes since there would be a lot of
voltage there ...


i would expect that 2" diameter legs would need to be shorter than all wire.
try one of the nec modelers to calculate how much. and yes, you need good
insulation at the feed point and the bottoms of the legs.

Doug,
Depends on the frequency to a large extent. If
the antenna is for above 10 meters you may see some
slight increase in bandwidth by using the tubing,
same for the 'shortening' of the elements. At HF
frequencies the 2" diameter tubing will have very
little affect on either bandwidth or shortening.
Why would the voltages be higher on tubing rather
than on wire?
'Doc

Didn't mean to imply the voltage would be higher for tubing than for wire.

Doug

"'Doc" wrote in message ...
Doug,
Depends on the frequency to a large extent. If
the antenna is for above 10 meters you may see some
slight increase in bandwidth by using the tubing,
same for the 'shortening' of the elements. At HF
frequencies the 2" diameter tubing will have very
little affect on either bandwidth or shortening.
Why would the voltages be higher on tubing rather
than on wire?
'Doc