On Fri, 24 Oct 2003 08:48:53 -0700, Frank Gilliland
wrote:

In , "(Scott Unit 69)"
wrote:

snip

But what about what Frank said? You know Tnom's test was a sham. I just don't
like to see people get cheated.

The X-terminator's coils work out to 1.27 uH for the 9 turn coil and 0.60 for
the 5 turn coil. The values of the coils and their positions on the shaft are
consistent with the design of a center-loaded vertical.

For those that don't already know, a loading coil is used to shorten an antenna
while still keeping it's electrical length at 1/4 wavelength. But the antenna is
necessarily less efficient because the coil radiates part of the power, and that
power is lost. Why is it lost? Using the X-terminator picture as an example, you
will see that the wire in the coil is oriented perpendicular to the antenna, so
any radiation from the coil is going to be horizontally polarized, while the
radiation from the antenna is vertically polarized. Some people might think
that's a plus because some people have horizontal antennas, but it's really
useless because it is radiated from 14 different wires (9 turns + 5 turns), and
none of them are in phase with each other. Since there is no receiver publically
available that can receive all those signals, put them back in phase with each
other and add them to the horizontal signal, the power radiated by the coil is
wasted. Nor can a receiver pick out just one signal from the fourteen. Even
worse, the coil concentrates the magnetic flux (just like any other coil) and
directs it right at the roof of the vehicle, which results in more lost power
due to eddy currents induced into the sheet metal. Any loaded antenna is a
trade-off between antenna height and efficiency.

The only difference between the X-terminator and any other center-loaded
vertical is that the former is built for kilowatts (and not very well at that,
as the conductors are chrome plated, so it's RF resistance due to skin effect is
higher than stainless steel, and much higher than bare copper or silver). There
is no way that this antenna will outperform the unloaded 102" stainless-steel
whip.

Tnom's test may or may not have been a sham -- he may have actually gotten those
numbers, but for reasons other than what he presented. Personally, I think the
only thing he tested was his imagination.



The X-terminator has its main lobe at bit higher angle than the whip
does. That may account for some of the differences.

Chrome has about the same conductivity that Stainless does, or at
least from the info I found. 3-15% for Stainless, 19% for chrome,
relative to copper.