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Old December 10th 07, 12:48 AM posted to rec.radio.amateur.antenna
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Posts: 492
Default Standing Wave Phase

On Dec 9, 3:27 pm, Cecil Moore wrote:
Keith Dysart wrote:
Except that I have offerred a number of examples
which you, the oracle, have declared are not
90 "electrical degrees".


If it is 90 electrical degrees then it is 90
electrical degrees. If it is not 90 electrical
degrees, it is not 90 electrical degrees. I don't
know how to make it any clearer than that.


I suspect you are correct there.

I, too, can subtract (43.4 + 10) from 90 and get
a number. This does not, by itself, a useful
proposition make.


It does if we know the reflected wave undergoes a
180 degree round-trip phase shift or else the
reflected wave would not be in phase with the
forward wave and therefore the feedpoint impedance
would not be purely resistive.

Please provide your algorithm in sufficient detail
that I can test it against the various examples.


It's the same as determining if an antenna is 0.5WL
or 1.5WL or 2.5WL or 3.5WL or ... Do you also have
a problem with that?


I use a measuring tape for that, so there is no
problem. But if I recall correctly, your definition
of 90 degress is not amenable to the use of
measuring tapes.

If the phase shift end-to-end is 180 degrees, the
device is 90 electrical degrees long.

If the phase shift end-to-end is not 180 degrees,
the device is not 90 electrical degrees long.

So far, each time you have provided a rule, I
have constructed examples according to the
rule which the oracle has declared are not
90 "electrical degrees".


I have provided no rule. Everything is common sense.


Everyone thinks they are full of "common sense" and
that few others are. Science is not advanced by claiming
common sense.

If you do not have articulatable rules, then you do
not even have a hypothesis, much less a theory.

If a dipole is 130 feet, it is 1/2WL on ~3.6 MHz.
If the antenna is 403 feet long, it is 1.5WL on
~3.6 MHz. Why do you have a problem telling the
difference between a 130 foot dipole and a 403
foot dipole?


No problem. But I am allowed to use a measuring
tape to answer that question.

And if you wrote a rule using measuring tapes for
this 90 degree stuff, I would have no trouble with it
either.

But if the best you can do is claim "common
sense", you can be sure that my "common
sense" will arrive at different answers than yours.

....Keith

 
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