[TowerTalk] Antenna Modeling Programs

[JC Smith]

>> 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?
>> 
>> Big Don
>Don,
>
>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.

Interesting.  I wonder why it is that there does seem to be a diffeence when
the wire is being used as the center conductor in coax cable.  Eg: the
difference in performance between LMR-400 and LMR-400 ultra flex.  The
stranded wire should have more surface area and thus better performance, but
the opposite is aparently true.  Then when you go from the 7 strand to the 19
strand center conductor (if you can find it) the performance supposedly goes
back to near that of the solid wire.

Joe Lanou, are you still lurking aroud out here?  Sorry if I got the name
wrong, but aren't you the Times Microwave Systems rep. I was corresponding
with a while back?  Can you shed some light here?  Also, any further word on
19 strand LMR-400?

73 - JC,k0hps@amsat.org



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