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Old April 7th 07, 05:43 PM posted to rec.radio.amateur.antenna
Cecil Moore[_2_] Cecil Moore[_2_] is offline
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First recorded activity by RadioBanter: Mar 2007
Posts: 3,521
Default Constructive interference in radiowave propagation

Gene Fuller wrote:
However, it shows that the null you believe demonstrates some permanent
interaction and annihilation of EM waves is simply a special case.


http://micro.magnet.fsu.edu/primer/j...ons/index.html

"... when two waves of equal amplitude and wavelength that are
180-degrees ... out of phase with each other meet, they are not
actually annihilated, ... All of the photon energy present in
these waves must somehow be recovered or redistributed in a new
direction, according to the law of energy conservation ... Instead,
upon meeting, the photons are redistributed to regions that permit
constructive interference, so the effect should be considered as a
redistribution of light waves and photon energy rather than the
spontaneous construction or destruction of light."

In classical, non-cosmic, non-relativistic conditions EM waves do not
interact in free space. This condition is so widely understood in the
scientific world that it becomes a prime candidate for argument on RRAA.


Florida State University seems to disagree. "Upon meeting"
in free space, the interfering photons are "redistributed".
RF waves are EM waves. Just because we cannot see them is
no reason to assert that they act differently from EM waves
that we can see.

Hecht, in "Optics", says about interference:

"At various points in space, the resultant irradiance can
be greater, less than, or equal to I1 + I2 depending on
the value of I12 ..." I12 is previously defined as the
interference term. Hecht's "various points in space"
seem to contradict your assertion that waves "do not
interact in free space".

From Born and Wolf: "Thus if light from a source is divided
by suitable apparatus into two beams which are then superposed,
the intensity in the region of superposition is found to vary
from point to point between maxima which exceed the sum of the
intensities in the beams, and minima which may be zero."

If "region of superposition" is not referring to the free
space point of interference, to what is it referring?

When one can see with one's own eyes the interaction of
two light beams in free space, how can you possibly deny
the existence of that interaction?
--
73, Cecil http://www.w5dxp.com