On May 4, 10:32*am, Cecil Moore wrote:
Art Unwin wrote:
I suspect that Corum made some approximations.

Of course, they are approximations. The wire
diameter doesn't even appear in the equation.
Quoting the Corum paper:

"A useful engineering *approximation* has
been found for the fundamental resonance of
helices ...".

"... an *approximation* for M has been determined
by Kandoian and Sichak which is appropriate for
quarter-wave resonance ... for helices with
diameters considerably less than a free-space
wavelength".

"We have found that this expression gives acceptable
results (errors less than 10%) for most practical
applications that involve wave propagation on
helical resonators ...".
--
73, Cecil, IEEE, OOTC, *http://www.w5dxp.com

Cecil you never once backed me up on Maxwell/lumped loads
saga on this group. Now you point to several improvisations on
obtaining
lumped load affects by other avenues where not one theory satisfies
the physics community. If one starts off with the acceptance of errors
in the range of 10 % where you are also allowed to jump from one
theory to another so the acceptable discrepancy can be satisfied then
this is dishonest with respect to physics.
As I have pointed out many times, Maxwell's laws do not pass rigourous
examination when lumped loads are introduced. With that said, I do not
quarrel your aproach with respect to degrees of antenna in terms of
approximations but when it is applied to antennas on this group
adherence to Maxwell is required, which is inclusiveness of all forces
as opposed to planar designs (yagi's) where liberties are taken in not
accounting for all forces within the arbitrary borders. It is this
very aproach which have allowed designs of antennas to move away from
the edicts of Maxwell and the equilibrium requirements of Newton which
provide for maximum efficiency.
It is the silence of you and other respected people on this group that
is responsible for the lack of advancement in antenna design over the
last hundred years by not adhering to classical physics.
Nothing personal intended, but this does exhibit a representation of
the engineers in this group in misleading other hams with respect to
this hobby.
Best regards
Art