[amsat-bb] Phasing lines for 2-m Yagi circular polarized project

John Toscano tosca005 at umn.edu
Sat Feb 11 21:14:27 UTC 2017

Yeah, it does get a bit complex with the phasing stubs and impedance
transformers, the need for coax of an odd impedance (70 ohms which doesn't
exist, so 75 ohms used as a compromise), etc.

That's why I advocated using a 2-port power divider, a device which
physically acts as the impedance transformer needed to connect two 50 ohm
antennas in parallel and remain at 50 ohms to the radio connection. And if
the "mechanical method" of getting the quarter wave offset between elements
is used, then no need to get coax feeders of different lengths by exactly a
quarter-wave after adjusting for velocity factor. Just two pieces of 50 ohm
coax of exactly the same length, which can be easily verified with
relatively simple test equipment, namely a dual-channel oscilloscope with
x-y plotting mode.

On Fri, Feb 10, 2017 at 8:28 PM, Kevin M via AMSAT-BB <amsat-bb at amsat.org>

> You may find this page very useful... I don't understand it all, but it
> sure educated me:  http://www.qsl.net/sv1bsx/antenna-pol/polarization.html
> 73, Kevin N4UFO
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