[Antennas] Why not twin lead?

Mon, 22 Apr 2002 01:31:23 -0400

> According to the ARRL Antenna Book, any feed line that is an electrical
> half-wavelength long will "reflect" the impedance at the feed point of
> the antenna to the other end of the line.  I believe that to be true.

   So?

> OK, so the question, then, is:  why not twin-lead for a 2m antenna?  If
> coax is so lossy at 146Mhz, then why do we not see more RS twin lead
> feeding things like J-poles?  Has anyone done this?

> I'm interested in any thoughts everyone might have...

  Twin lead was invented for VHF and it does work fine.

RG-8 and better wasn't made for VHF, but if kept short works just fine,
without a match problem at the transceiver end.

  To match 300 or 450 or 600 Ohm line:

   Make a 1/4 wl stub just like the bottom 1/4 wl of a "J" pole antenna
(18 inches) Connect the RG-8 from the rig as usual and connect the twin
lead about twice higher. (from the short at the bottom end)
Use very small SS hose bands to secure it to the copper tubing,
so you can slide the two cables up and down to get the best match.

       73 (= Best Regards) de: Ron [email protected]
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