[Elecraft] easy source of static dissipating work mat?

[Alan Bloom]

On Thu, 2008-12-11 at 21:45, Dr. James C. Garland wrote:
> > > 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

Yup, the resistance of a two-dimensional surface is dimensionless,
typically measured in "ohms per square".  If you have a square of the
material with electrodes along two opposite edges, the measured
resistance is independent of the square size.  For example if you double
the size then both the length and width double, cancelling each other
out.

Al N1AL