Roy:

[snip]
That's a great attitude for a politician, philosopher, or biblical
scholar. But engineers and scientists depend on universally understood
technical terms in order to communicate. I'm free to say that my car gets
a gas mileage of 30 miles/hour and weighs 420 miles. But it wouldn't be a
smart thing to do if I intend to convey information.

[snip]
Sorry, it doesn't. An unavoidable side effect of the synchronicity
change is that the amplitude of the E field still changes at a 1 GHz
rate, going through a complete cycle from max to zero to max to zero to
max each nanosecond. A circularly polarized wave doesn't change
amplitude with time. A non-circular elliptical wave changes amplitude
but not fully to zero each cycle.
[snip]

Here there is a bit of fuzziness...

I agree that the E field of a wave is always changing at the RF carrier
frequency
since it is an AC waveform. Alternating current is always changing! And
so a
1 GHz carrier will always have an E field that oscillates back and forth
at the
carrier (center?) frequency when analyzed by a (linear) polarimeter.

I disagree with you that a circular polarized wave has a constant E
field.

Even in the case of a purely circularly polarized the E field still
oscillates
at the carrier (center?) frequency when analyzed by a linear polarizer.

i.e. if a purely CP wave is received on a linear polarized antenna the
detected E field (Volts per meter) will be observed to be oscillating
at the carrier frequency. However if received on a purely CP responding
antenna this oscillating E fileld will appear to be constant.

The E field vector can be considered to be similar to the image of a
spoke on a rolling wheel. The radius of the spoke is constant, but
it's projection on the ground over which the wheel is rolling will
always be oscillating in length.

When you receive a circularly polarized wave on a linearly polarized
antenna, you're seeing only the component of the wave that's linearly
polarized in the orientation of the antenna. This is exactly the same
process as filtering a complex waveform. You've removed part of the field
and are observing what's left after the filtering process, then drawing
conclusions about the original waveform based on those observations, much
like listening to a concert orchestra through a long pipe and deciding
that orchestral sound is very ringy and limited in tonal range. It would
benefit you to gain a bit of education about circularly polarized waves.
You'll find that a circularly polarized wave can be created from (or
broken into) two linearly polarized waves oriented at right angles and in
phase quadrature. So each of the components has a time-varying amplitude,
but the sum, which is the circularly polarized wave, has a constant
amplitude but time-varying orientation. Your linear antenna filters out
one of the components, leaving you to observe only the other.
[snip]

Yes indeed, we must be talking at cross purposes, since we seem to
have no disagreement on any of the above. I don't see where we differ at
all!

[snip]
Would the rate of spin have to be 99-44/100 percent of the synchronous
frequency? Or would it have to be closer than that?

At what magic spin frequency would the two be indistinguisable.
[snip]

I would repeat the above question in a slightly different way...

How much frequency, or for that matter phase, difference must there
be between the mechanical spin frequency and the carrier frequency
before you could tell the difference between your "conventionally defined"
circular polarization and my definition?

If my antenna was spining with an angular velocity within say,
0.000000000005% of the carrier frequency, would that do it?

Or perhaps my spin rate would have to be closer to the carrier
frequency than that?

If so, then how close does it have to be to qualify to be called
circular polarization under (your) traditional/conventional
definition?

[snip]
What you'll end up with is amplitude modulation with the modulating
frequency being the beat note between your spinning speed and the wave
frequency. This creates sidebands. You'll see this when the sidebands are
within the bandwidth of the helix. Outside that, the helix will filter off
the sidebands and you'll just see the "carrier" -- the original wave with
no modulation.
[snip]

Hmmm... Yes, I agree and that's partially correct, but some of the above
paragraph is
somewhat "fuzzy" to say the least.

That helix must be a very sharp [brick wall???] filter, no?

Let's get real here, no practical implementation of any kind of physical
filtering
mechanism can filter with infinitely sharp transition bands. It just
doesn't happen
in nature.

[snip]
Here's a really neat little trick you might want to add to your bag --
superposition. As I mentioned, you can create a circularly polarized wave
from two linearly polarized waves. The linearly polarized waves are of
course normally time-varying. As long as the propagation medium is linear
(such as air), superposition says you can split the circularly polarized
wave apart into two linearly polarized waves, study and analyze how they
propagate, then add the two components back together again after the
propagation. This is, incidentally, a very simple way to see what happens
when a circularly polarized wave reflects from a surface -- analyze the
linear components separately and add the results.
[snip]

Heh, heh... Superposition is not a 'trick' it is a well known principle and
Roy, I agree with all of the above!

What's your point?

Bringing up superposition is fine, but you seem to raise the concept of
superposition simply as a digression here, not as a means of disproving my
assertion that mechanically spinning a linear antenna is tantamount to
conventional circular polarization.

[snip]
That's about all I can do at this end. I can't make you actually pick up a
text and learn about circularly polarized waves, and until you do, you'll
have some fundamental misconceptions about them.
[snip]

Hmmm... that was a cheap shot! Unfortunately I agree, YOU cannot
make me pick up a text.

However, I can make myself do so myself, and... it may (or may not)
interest you to know that I have done so on many occasions.

In fact I have picked up several such texts, addressing such subject matter
authored by Physicists and Engineers ranging over subjects
as diverse as radio frequency antennas and optics.

Would it impress you if I sent you a picture of my personal library
of several hundred volumes, which contains perhaps a dozen or more
textbooks on electromagnetics. Since I have been examined on these
subjects at graduate degree levels by the faculty at several duly accredited
Universities it seems that there is some evidence that I may have read and
understood at least a few paragraphs from those texts that I "picked up"!
[smile]

[snip]
Guess I'm one of those folks who someone described recently as "having the
common sense educated out of me". It's served me well, since it's enabled
me able to spend a career designing a wide variety of state of the art
electronic circuits and antennas, successfully mass produced, which work
as designed. But I know it's not for everyone.
[snip]

Hmmm... I too have spent (wasted?) most of several decades designing
electronic products and equipment for international markets sold in more
than 40 countries with at total sales volume exceeding $5BB dollars.

And it seems in today's world that if you combine that Engineering
experience with $2.50 you can buy a cup of coffee at Starbucks!

Now that we have suitably set the stage, lets get back to the common
sense Engineering question at hand!

All I need is a number!

Perhaps I should regurgitate the statement of Lord Kelvin about knowledge
that dear departed Reg used to quote. You know... the one about quantifying
things, the one that says you know nothing unless you can put a number to
it!

Do I really need to do that here? Reggie dear friend, are you watching from
above?

Roy, please answer the following common sense Engineering questions, just
how close must the angular velocity of my spinning antenna be to the carrier
frequency before YOU will allow it to be called circular polarization?

A simple numerical value in percentage form would do fine!

[smile]

-- Pete K1PO
-- Indialantic By-the-Sea, FL