[Elecraft] RE: zip cord as antenna wire

[Don Wilhelm]

Joe and all,

My information base rates the following commonly available parallel feedline
as follows:
1) speaker wire or zip cord - very bad;
2) 300 ohm TV twinlead (solid dielectric) - good but varies in quality
depending on manufacture;
3) 300 ohm window line - better and more consistant;
4) 450 ohm window line - even better;
5) open wire ladder line (close spaced with frequent speaders) - much
better;
6) open wire ladder line (wider spaced with few spreaders) - the best.

The window line is usually chosen over the ladder line because it is not as
demanding to install.

Additional note - at VHF/UHF wide spacing of the balanced conductors can
turn the transmission line into a radiator - the spacing must be
significantly smaller than the wavelength.

The zip cord wire can be used for the antenna proper with no ill effects
that I know about.  The length may vary a bit from theoretical length due to
the insulation, but that is true when using any insulated wire for an
antenna - just tune it for resonance, but for a non-resonant antenna, it
doesn't matter much anyway.

73,
Don W3FPR

----- Original Message ----- 

> If zip cord or speaker wire is bad for a transmission line, what if I use
> 300 ohm tv lead as the transmission line to a 44 foot center fed dipole?
Is
> 300 ohm any better ?
> de Joe, aa4nn
>
> > I had known that this means that zip cord makes bad transmission line.
> > Does it also imply that it makes bad antenna wire?  That is, does an
> > unzipped cord, single wire, radiate much worse than wires with other
> > kinds of insulation, when used in a tuned dipole?
>