On Wed, 13 Dec 2006 11:47:17 -0800, Richard Clark
wrote:

....
There is no either/or offered in the first place. Your mistake of
feed point relationships has overlooked the "third" wire of the
seemingly two wire load. That "third" wire (the coax shield) runs in
very close proximity to the car body for as great a distance as any
capacitor lead described above. This shield/body relationship offers
vastly more capacitance than any mount.

The "third wire" (being the current flowing on the outside of outer
conductor of the coax) is more properly a transmission line itself,
possibly a leaky (ie radiating) transmission line.

For example, were you to place a magmount on a large metal ground
plane (that is a sheet, not wires), and lay the coax straight from a
magmount to the source whose ground terminal is bonded to that ground
plane, the effect of the coax will depend on the electrical length
formed by the outside of the shield of the coax and the ground plane.
Consider the effects of the transmission line so formed were it an
electrical quarter wave, and an electrical half wave (taking into
account any bulk shunt capacitance at the magmount due to the mount
itself..

Who knows what happens in actual magmount installations? They truly
fall into the category of "works" on lower frequencies, whatever
"works" means to the individual.

Owen

....
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