Richard Harrison wrote:
Cecil. W5DXP wrote:
"Unfortunately, I must disagree (very slightly) with Kraus."
I had invited readers to the helical antenna pages of Kraus to support
my wave advance comparison to the progress of a threaded bolt. I had
looked at page 229 in the 3rd edition with its Figs. 8-8 and 8-9 or at
similar figures in an earlier edition.
Upon looking agin, I still believe the figs. support my bolt comparison.
In any case, I`d study long and hard before arguing with Kraus.
No doubt, your bolt comparison is valid when each turn on
the "coil" is one wavelength long. But what happens when
each turn is 0.006 wavelength? Do you reckon something
might change?
Hopefully, I am not disagreeing with Kraus. It appears that
the question is: Does Kraus' one wavelength per turn helical
antenna have the same VF as a 75m Texas Bugcatcher loading coil?
Kraus' own graph shows that if one varies the turn circumference,
the phase velocity is not a linear correspondence. I would suggest
that lack of linear correspondence occurs in the 75m Texas Bugcatcher
coil. We cannot tell what the exact phase difference would be at
0.006 wavelength per turn, but the trend seems obvious to me.
--
73, Cecil
http://www.w5dxp.com