On Thu, 3 Apr 2008 12:45:43 -0600, "Bob Crantz"
wrote:


"You" wrote in message
...


Willie, what you know about 2.4 Ghz RF Antenna Propagation and Path
Design, is smaller than you IQ, which you amply demonstrate every
time you post. Best you leave this to the folks, who actually have
Professional Experience, in the field......

You could start by using your Professional Experience and explaining what
Wilbur has done wrong and why what he observes cannot be happening. As to
any professed expertise on radio wave propagation all I've seen here are
antenna installers. I'm sure they are competent at installing antennas but I
really doubt they could make any accurate predictions of radio signal
propagation based upon what knowledge is required for installing antennas.
Thinking an antenna installer is expert on radio path propagation is like
thinking the person who drains the bedpan in the hospital is a doctor.

Even Wikipedia states:

http://en.wikipedia.org/wiki/Fresnel_zone

"If unobstructed, radio waves will travel in a straight line from the
transmitter to the receiver. But if there are obstacles near the path, the
radio waves reflecting off those objects may arrive out of phase with the
signals that travel directly and reduce the power of the received signal. On
the other hand, the reflection can enhance the power of the received signal
if the reflection and the direct signals arrive in phase. Sometimes this
results in the counterintuitive finding that reducing the height of an
antenna increases the S+N/N ratio.

Fresnel provided a means to calculate where the zones are where obstacles
will cause mostly in phase and mostly out of phase reflections between the
transmitter and the receiver. Obstacles in the first Fresnel will create
signals that will be 0 to 90 degrees out of phase, in the second zone they
will be 90 to 270 degrees out of phase, in third zone, they will be 270 to
450 degrees out of phase and so on. Odd numbered zones are constructive and
even numbered zones are destructive.[2]"



Please Note the following: "On the other hand, the reflection can enhance
the power of the received signal if the reflection and the direct signals
arrive in phase. Sometimes this results in the counterintuitive finding that
reducing the height of an antenna increases the S+N/N ratio"

Based upon your Professional Experience and all that you know about "2.4 Ghz
RF Antenna Propagation and Path Design" can you refute the above
statement? Did you get the part about "Odd numbered zones are constructive"?
That means they increase the received signal. By lowering his antenna he has
increased reflection in the first Fresnel Zone - "1" is an odd number the
last time I looked and his signal should increase.

If there is some new type of non-causal electromagnetics I'd love to hear
about it, so fill me in.

BTW "2.4 Ghz RF Antenna Propagation and Path Design" should be stated as
"2.4 GHz Radio Wave Propagation and Path Analysis". Antennas don't propagate
and paths are usually analyzed, not designed.

Wilbur's observations are supported by proven science.



That certainly soils Glen Ashmore's credibility. One would begin to
wonder if his success is built more on luck than knowledge. Here's
another website offering the same arguments:

http://www.zytrax.com/tech/wireless/fresnel.htm

It is really sad to see someone attempt to sully another's reputation
with misrepresentations and wind up ruining their own.

JT