On Tue, 09 Aug 2005 16:37:38 -0400, Walter Maxwell
wrote:

How do you
suppose that had it not been for wave interferencethe energy would
have continued on in a particular radial direction,

Hi Walt,

What stopped it if not a physical barrier?

but due to the
interference the result was a null

A null is not the absence of energy, but is the combination of equal
and opposing forces. If you were the Ref at a title bout, and stepped
between two punches of equal magnitude; then you wouldn't move very
far, the motions would cancel, but most would doubt you'd be up again
before the "count."

Nulls are evidenced quite clearly in bridges of many designs. They
may balance between huge potentials (energy), but evidence absolutely
no current (or power from energy times current). If you unplugged the
equipment from a bridge, the absence of current would not be an
indication of a null. Nulls within the context of engineering
necessarily carries the implication of energy present.

in that direction and an increased
amount of energy in the opposite, or forward direction, achieving gain
in that direction?

Linear systems do not exhibit "gain." The combination of forces are
due to the total field in comparison to the region of interest.

It is by similar simplifications that we have contributors here who
offer that the radials of elevated ground planes do not radiate
energy. Their contribution to producing a power at a remote load may
cancel such that no power is evident, but this does not negate the
radiation nor the energy present.

73's
Richard Clark, KB7QHC