Although Tim does say "ladder line (open wire)", so I know what he means, I
think there could be some confusion about this. I could be wrong, but I think
in the usual ham lexicon "ladder line" often is used for what I call "window
line", i.e. polyethylene insulated twinlead with windows poked through the
ribbon. The loss characteristics of these two is quite different. Window line
used with elevated SWR can be very lossy.
Likewise, the loss in tuners is often dismissed as negligible, when it too is
not. Tim's Matchbox with air-wound inductors and air capacitors is very
efficient, the average T-network with relay-switched toroid inductors and
capacitors may not be. And then there are the baluns....
I wrote about this in a somewhat antiquated draft of a paper published in one of
the ARRL Antenna Compendiums. I don't maintain a personal website, but someone
else thoughtfully posted it here:
https://www.casa.co.nz/equipment/Aerials/Ladder-Line/LadderLines-7132619_9p.pdf
Wes N7WS
On 6/16/2025 6:34 PM, Tim Duffy wrote:
A couple of notes about using a 80 meter dipole (center fed 130 feet long) on
multiple bands fed with ladder line (open wire).
Using a good open wire tuner - results in a very low VSWR presented to the TX on all
bands. Even a used Johnson Matchbox (my favorite) is affordable and with one wire
antenna - you can cover 80 through 10 meters easily. Even though the Antenna feedpoint
impedance is high, so the VSWR on the openwire line is high, it doesn’t matter
- because the feedline loss is so small due to using ladder line. This is not the case
for high VSWR on coax fed antennas that are used on multiple bands without traps or
other techniques to keep the VSWR low.
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