[Elecraft] easy source of static dissipating work mat?

[Dr. James C. Garland]

> > I didn't find a specification on the electrode size, but in the photo of
> > a popular tester they look to be maybe 3 or 4 inches in diameter.  For
> > my test, the electrodes were two saucepans, each about 7 inches in
> > diameter and weighted with 5 pounds

When measuring the resistance of a two-dimensional conductor (like a mat),
the resistance can be measured with point contacts, such as ordinary test
meter probes. One of the interesting properties of two-dimensional
conductors is that the measured resistance is independent of the spacing
between the probes. In other words, one will get the same measurement on an
ohmmeter if the probes are one centimeter apart as if they are one meter
apart, provided the mat is larger than the probe spacing. 

This result may seem counter-intuitive, but it makes sense if you think
about the lines of electic current that flow between the probes. Widely
spaced probes have more area for the current to flow into, thus compensating
for the fact that the probes are far apart. Thus the resistance is an
intrinsic property of the conductor and not of the geometry of the measuring
setup. Interesting, no?

73,

Jim W8ZR