I built a so called "Super J-pole" which is really two stacked
collinear half
wave antennas with a quarter wave phasing stub between them. The
design is by
N7QVC and it can be seen at http://www.n7qvc.com/amateur_radio/
copper.html. I
also placed a photograph of a representative build in the photo
section of this
reflector at
http://groups.yahoo.com/group/amateu...um/1449680574/
pic/3362107\
0/view?picmode=&mode=tn&order=ordinal&start=1&count= 20&dir=asc.

I have had good results with this antenna but I wanted to make it into
a dual
band antenna that would work on seventy centimeters as well as on two
meters. I
was wondering if I could use a technique developed by Edison Fong,
WB6IQN on
this antenna in the same way he used it on an ordinary single half
wave J-pole.
What he did is to place an open quarter wave stub at the top of the
two half
wave lengths for seventy centimeters. That stub limits the UHF signal
to the
two half waves length at UHF of the antenna. It seems like it would
work from
having read his paper on the combination two meter and seventy
centimeter J-pole
antenna. That would give the antenna the same gain on seventy
centimeters as a
J-pole that is just for that band. For reference I have placed WB6IQNs
paper in
the files section of the newsgroup at
http://f1.grp.yahoofs.com/v1/
kL6QTZLk1DQjM_Cn3vuvnsLUIuEsvRHSqUZyX2mw294a7mYKkc \
FBIXXlRY_6QxreqNWVpn0b7Dogiw9LafU63W429yoO/DBJ2_port_art.pdf.

My first question is does anyone see any reason why this would not
work?

My second question is how would I construct the stub into a copper J-
pole.
Since WB6IQNs J-pole is a wire antenna, with or without a plastic
radome, he
used a piece of Coaxial cable as part of his two meter wire with the
shield at
the end of the seventy centimeter portion of the antenna shorted to
the two
meter radiator and the bottom of the shield, which is a quarter wave
at UHF
below the top of the UHF segment, open relative to the two meter
radiator.
Could I just use a full quarter wave stub made from a copper T, a
street L, and
a short length of copper pipe turned back down along the two meter
radiator? (A
street L is a ninety degree bend formed to allow it to be close
coupled to an
adjacent fitting without a pipe nipple in between.)

My third question is if instead of shortening the lower VHF half wave
electrically to a UHF length I found a way to short out the quarter
wave phasing
stub between the two VHF half wave radiators to UHF signals thus
giving UHF
signals three full wave lengths of radiator to use would the gain be
worth the
effort. To provide the shunting of the VHF quarter wave phasing stub I
was
GUESSING that a half wave UHF coupling stub might work.

I freely admit to being out of my depth; or as a mariner might say off
my
soundings; here. So I'm fully prepared to hear that the UHF half wave
coupling
stub would not work as a shunt for the UHF signals to get past the VHF
quarter
wave phasing stub. I have no pretense to any expertise. I'm trying to
learn.
Laugh all you want but if it won't work please tell me in neophyte
decipherable
language why not. If you have any guidance to offer it would be most
welcome
but please keep the fog index down to the degree you are able. Thank
you in
advance.

--
Tom Horne, W3TDH