L.B. Cebik wrote:
<You can also use what some called closed-sleeve coupling, with a pair
of parallel wires between the main and subsidiary element. Because of very
close spacing, the wires do not act wholly as a standard transmission line-
indeed, the coupling tends to predominate.>
I found very interesting the fact that current on main driven element tends to
drop to zero at the points where tips of coupled element are parallel to main
element. That makes me believe that in some way this coupled element act as
simple trap as we all know that open half wave transmission line has high
impedance points on the ends same as parallel LC circuit. Hence there is no
that much loss like in conventional traps.
You said that because very close spacing wires are not acting wholly as
I think that spacing of 10.75 at 21 MHz (Force 12 C-3) and 6" at 28 MHz
(Explorer 14) is quite big to avoid radiation of two wire transmission line.
Maybe it was typo, if not please correct me if I am wrong.
Danny Horvat T93M
My congratulations on your great antenna site and thank you for sharing that
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