Owen Duffy wrote:
So, NEC can model your helical so long as your helical is one that NEC
can model!

A lot of useful information can be had this way. Here's
one such implementation that segment checks OK and
illustrates the ~68 degrees of phase shift through the
coil on 7.15 MHz.

http://www.w5dxp.com/coil512.EZ

... we don't know a
measured value for Tom's coil anyway or the true stand alone self
resonance.

I tried to get him to measure the self-resonant frequency
using the coil as a monopole over a ground plane. Corum's
equation says the coil has a VF of ~0.033 giving it an
effective length of ~25 feet or an electrical 1/4WL around
10 MHz.

The measured self-resonant frequency for my 75m Texas
Bugcatcher coil was around 6 MHz. It's calculated VF
was around 0.02.
--
73, Cecil http://www.w5dxp.com