That's a standard quarter wave coaxial choke that has been in antenna
books for several decades in one form or other. I used that technique
on a triband quad (with separate feedlines) more than 50 years ago.
Off the top of my head, though, I think your version requires that the
driven element not be isolated from the boom. Not sure it would work
with the driver isolated from the boom. I'll have to draw it out later
to double check.
73,
Dave AB7E
On 6/28/2020 3:10 PM, Richard (Rick) Karlquist wrote:
The simplest way to make a 50 MHz common mode
choke is to use 56 inches of coax and connect
one end to the feedpoint and connect the shield
of the other end to the boom. Then connect
your regular feedline to the end of the
56 inch cable. Let the coax hang down in a
lazy "U" away from the boom. Whatever you do,
don't be "neat" and tape it to the boom.
I suspect this configuration is somewhere
in the ARRL VHF handbook.
73
Rick N6RK
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