70 ohm matching stubs
 

In a recent artical in QST there was an antenna where a cross was made out
of pvc pipe and wire was looped around it to make loop antennas. One loop
per band. Then a 1/4 electrical wave of 70 ohm coax was used to make a 100
to 50 ohm match. This was done for several bands. That made him use 5
feedlines for the 5 bands he used. I know , could always use a remote coax
switch.

I have not given it much thought, and don't know if the lengths would reach,
but assuming they would (could always use multi 1/4 wave segments), has
anyone thought of using one long piece of 70 ohm coax and tapping it with
several T connectors at the correct 1/4 wave lengths for each band and then
feeding it with one piece of 50 ohm feedline ? I know there will be a small
bump in impedance with a 50 ohm T, but should not be too much.

This wold make it similar to a fan type dipole except to get to 50 ohms
only one piece of 70 ohm coax would be used with several taps on it.

Also if this would not work, I am planning on a 2 band version and thinking
of using a 1/4 wave matching for each band, but bringing the feed ends of
the 70 ohm segments together with a T and feeding it with one piece of 50
ohm coax.
The bands would be the one a 18 mhz and 24 mhz as I have a triband beam for
20,15, 10 meters.