Interesting stuff FFF - I'll have to do an ATPL (!) or look up a paper...
Evo: TACAN is I think much like VOR, with compatible DME, but on different frequency band. I did work on TACAN receivers also - but can't remember much detail... The expression VORTAC,
AFAIK, is used in the US to indicate a VOR with co-sited DME, but I am not 100% sure about this....
Now, here's a couple of photos of the "capacitive hat" style vertical NDB at Fort Carre, Antibe, on the approach to Nice:
(The detailed close-up shows it appears to have both capacitive and inductive loading elements near the top...)
Andy