jawod wrote:
In the latest QST there is an article on a Window line twin lead antenna
that uses relays to switch sections in and out of a dipole configuration
to allow multiband use. (DC is inserted into the coax to activate the
relays.)

Sounds interesting to me.

But...the twin lead is connected directly to coax with no balun. Isn't
this a mismatch? I wonder about significant RF coupling to the adjacent
dipole sections through the relay assemblies. Also, I couldn't tell if
the window line was shorted into a loop at the ends or not.

It is not a folded dipole.

The two sides of the ladder line are connected together at RF at the
input by capacitors C4 and C5 in the splitter making it look like a
slightly fat, ordinary dipole.

If you want to know about RF coupling on the adjacent elements, you
could model it with the demo version of EZNEC.

--
Jim Pennino

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