Yes, that's what I found. Even though a neat solenoid looks like it is a long coil of 'the same stuff' there are end effects and departures from simple transmission line behaviour. But I found that I could still produce a reasonable physical model that behaved well when put through its paces on a simulator. The best behaved model was the VNA 2 port model but it is just a black box model and maybe this is dodging the issue.
If I had to be critical of the David Knight paper, I'd suggest that there is very little there that would help someone make a well behaved inductor model that explores the inductor performance up in the region of these resonances. The goal of the paper seems to be one of pinning the tail on the donkey in terms of calculating resonances. But this is only of limited use for everyday engineering work. A well behaved (wideband) model that doesn't fall apart when scrutinised on a simulator is of much more value I think
