Hello,

Following link http://qucs.sourceforge.net/tech/node93.html gives an
expression for the characteristic impedance of a twisted pair. It also
includes a correction on effective permittivity for the twist angle
(or twists/length).

I have a document from Universidad de Buenos Aires, www.fi.uba.ar,
"Líneas de transmisión" (transmission lines) this document explicitly
mentions that the twist angle must be in radians.

However, when assuming twist angle of 45 degrees (0.785 radians, that
is tight twisting) and a relative epsilon of 3, the formula gives a
decrease of Z0 of less then 0.1% (w.r.t. almost no twisting). This
result doesn't match my experience and experimental data from other
recourses.

When entering 45 degrees, the result is a reduction of Z0 to 70% of
non-twist value, which sounds better to me.

Does somebody have access to the original document (or know from
experience) to figure out whether radians or degrees must be used for
the formulas in the link mentioned above?

Thanks,

Wim
PA3DJS
www.tetech.nl
Please remove abc from the address in case of direct reply.