[Antennas] Why not twin lead?

Mon, 22 Apr 2002 11:42:25 -0500

I once had a 10-el yagi on 2 meters with 200-300 (?) ohm impedance, fed
with RG-58, using a 4/1 balun also made from RG-58.  See the ARRL Antenna
Handbook for details.
Dave          W9LYA
What wrought doG hath?

On Mon, 22 Apr 2002 07:12:37 -0700 (PDT) Pat W <[email protected]> writes:
>  It would be nice to be able to use twinlead, or
> ladderline for Vhf.  THe problem is that when the Z0 of
> the feedline does not match the Zin at the transceiver,
> the Zload at the antenna gets transformed to something
> other than 50 ohms.  Using 1/2 wavelength of line
> should solve this but how to you know what is an exact
> multiple of 1/2 wavelength ?  If you're off by a few
> inches that could really mess up your SWR.
>  An alternative would be to have transformers at each
> end of the twinlead to step up/step down the load
> impedance, but, I haven't seen anything published on
> what materials to use at VHF.  I can build really nice
> broadband(160m-10m) 4:1 or 9:1 transformers for HF but
> VHF is a totally different animal.
> 
>  Pat W0OPW
> 
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