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.

Any comments?

Thanks

John
AB8O
The impedance of the dipole is in the 200 to 600 ohm range. The
transmission line is a fair match for the antenna element. A transmatch
is required at the transmitter end though.

Dave WD9BDZ

"David G. Nagel" wrote in message
...
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.

Any comments?

Thanks

John
AB8O
The impedance of the dipole is in the 200 to 600 ohm range. The
transmission line is a fair match for the antenna element. A transmatch is
required at the transmitter end though.

Dave WD9BDZ

It's not a folded dipole. Both wires are fed in phase, and the second wire
is needed for a DC return only.

Tam/WB2TT