Owen Duffy wrote:

[snip]


If you use the inductance calculator at
http://hamwaves.com/antennas/inductance.html to determine Beta, you get
2.008 rad/m. The coil is .254m long, so that suggests a one-way phase
delay of 0.51 rad, or 29.2°. Some suggest that this coil will replace the
equivalent electrical length in a quarter wave monopole to shorten it
with inductive loading, and irrespective of the position of the loading
coil... which is not consistent with experience that a larger loading
coil is needed the further it is from the base.



Something to consider about the Hamwaves calculator. This Corum
calculation appears to analyze everything in terms of the "n=0 sheath
helix waveguide mode", whether it is appropriate or not. This web page
does not contain any of the caveats that were in the Telsiks article.
Try some extreme numbers and you can see that the expected results do
not occur.

It is somewhat ironic that the work of David Knight, referenced by
Corum, appears to refute quite of bit of Corum's claim. Knight
recognizes, as many people do, that there is a transition between a
lumped model regime and the quarter wave resonance regime. The resonance
model does not apply when the coil is shorter or the frequency is lower.

73,
Gene
W4SZ