SGC coupler to Dipole feedling question
"Ed_G" wrote in
. 192.196:
No, I wouldn't say "shield" would be a proper term, either.
But I
would suggest that a "cancellation" similar to radiation in a
balanced feedline, would be pertinent.
Then I will leave you to your view that the system is balanced.
Owen
I would have preferred an explanation of your view on why it
wouldn't
be, but I thank you for all your prior discussion.
From my first post on the topic:
"If Ed connects parallel line from the centre of the dipole to the hot
and
common terminals of the ATU, there is likely to be common mode current on
the parallel line adjacent to the ATU. If the only connection on the tx
side of the ATU is the coax, then it will also have a common mode current
adjacent to the ATU and near enough to equal to the common mode current
on the other side of the ATU."
Sure, you can fabricate a parallel line from two coaxial lines, it just
has much more loss than a conventional air spaced line... and although it
is short, you intend operating it at extreme VSWR. The shielded twin line
you synthesise does not have any magic properties in supressing or
shielding feed line radiation.
Note that I am avoiding the term balanced line that some have used.
Balance is not forced by line geometry, but is a result of the
environment, so balanced lines are balanced by external factors, not the
line geometry.
Owen
PS: I wonder if you had considered end feeding the Inverted V with the
ATU. IIRC you had a sheet metal roof. You could just fix the tuner to the
roof, connect the ground terminal to the roof sheet, and take a wire from
the ATU output terminal to the end of the inverted V (which is a
continuous conductor across the apex). This is an unbalanced load
connected to an unbalanced output. Is that too easy?
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