Richard Clark wrote:
A lumped circuit has only one resonance. A transmission line has an
infinite number. It certainly isn't necessary to impose a strict test
of this. Finding second, third, and fourth harmonics for an inductor,
in situ, would certainly be compelling evidence of transmission line
behavior.

Using the same coil stock as W8JI's 100uH coil, I just set up
a 50 uH coil on a mag mount sitting on my metal desk. Its
first solid resonance was 9 MHz (1/4WL), its second solid
resonance was 27 MHz (3/4WL), and its third solid resonance
was 45 MHz (5/4WL). In addition to those, there other soft
spots and double dips along the frequency line.

W8JI reported something happening at 24 MHz as well as self-
resonance at 16 MHz. He was apparently not testing it over
a ground plane like an automobile body. That automobile
ground plane drops the VF much lower than an isolated
coil's VF.
--
73, Cecil http://www.qsl.net/w5dxp