On Tue, 09 Aug 2005 13:56:40 -0700, Richard Clark
wrote:
Hi Walt,

What stopped it if not a physical barrier?

Richard, there is no physical barrier in an antenna array that changes
the shape of the radiated pattern. The barrier is caused only by
destructive wave interference.

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."

In a title bout two punches of equal magniude are coming from opposite
directions. The energies in the two punches is dissipated in the
noggins of the morons who got into the bout;. The resulting null is in
reducing the already worped brains to zero.

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.

We're not talking about nulls in bridges, we're talking about energy
controlled in desired directions, reduced in some directions, with the
energy lost in one direction adding to that in another; but you know
this.
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.

Well, Richard, there is no non-linearity in the formation of antenna
radiation patterns. Are you saying there is no 'gain' when energy is
taken from one direction and pushed into another? With respect to
radiation patterns, 'gain' is relative, and not consideredas an
increase in power. But you know that too.

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

My comments are totally unrelated to elevated ground planes. I'm only
trying to prove to Jim that wave interference DOES cause energy to
shift direction without any aid of a physical entity. The only cause
of the change in direction of energy radiated from an array of dipoles
is wave interference, the interference between the waves emanting from
the different dipoles.

Walt, W2DU