Cecil Moore wrote:
5.5 MHz: 14.1 deg, 5.89 MHz: 15.7 deg, 6 MHz: 16.2 deg,
7 MHz: 21.4 deg, 8 MHz: 29.5 deg, 9 MHz: 45.9 deg,
10 MHz: 89 deg, 11 MHz: 141.4 deg, 12 MHz: 163.0 deg,
13 MHz: 172.3 deg, 13.7 MHz: 183.82 deg.

I just bought Mathcad and am trying to learn to use it.
The graph of the above data is really interesting. Somewhat
like a sine function, this curve has an inflection point
around 10 MHz where the phase shift is changing most rapidly.
On either side of 10 MHz, it doesn't change as rapidly.
10 MHz appears to be the 1/8 wavelength point where
|Z0| = |XL|.
--
73, Cecil http://www.qsl.net/w5dxp