[TowerTalk] Antenna Modeling Programs

[Big Don]

On Thu, 13 Mar 1997, L. B. Cebik wrote:

> > How about something that models the difference between stranded wire and
> > solid wire (for the same length of wire), or doesn't the scientific
> > community feel any such RF-radiation differences exist?
> 
> To the best of my knowledge, at HF most sources hold the view that there
> is no significant difference between solid and stranded wires.  Certain
> stranded wires are constructed in such a manner that a given nominal wire
> size may not be true to the diameter charts.  However, unlike Litz
> wire--which is effective below about 0.5 MHz, stranded bare stranded wire
> at HF is considered by most to have the same properties as comparably
> sized solid wire.  Wire contact and field intensity would place the
> maximum RF current on the exposed surface of the wire.  I have found no
> source that accounts for any possible differential in exposed surface
> area.
> 
> If a difference did exist, NEC could not model it.  Wires closer than
> 0.001 wl are considered connected at junctions, and overlapping wires are
> generally considered illicit and produce erroneous results, enless
> error-trapped by a particular implementation.  If there is any significant
> difference between stranded and solid wire, it would take a
> pre-calculation diameter adjustment to the solid size with the closest
> performance.

Without any formal test data available to actually pin it down, Big Don
based that question on what appeared just from casual observation to be
performance differences between cubical quads built using solid and
stranded wire with the same loop lengths.  There may well in fact be no
difference. However, the stranded wire being twisted, and the current
traveling on the twisted surfaces perhaps generating some inductance or
other complex interactive effect, particularly at the corners of the
loops, conceptually, is perhaps of interest.  

Wondering if the experts are basing their opinions of "no difference"
on tests using only straight lengths of wire??  Nice wild goose chase for
you perfessers out there to send some wild-eyed EE grad student off on.

Big Don


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