Buck wrote:

The Yagi is a beam typically of similar length elements which will
almost look like a rectangle when all the outside tips are connected
by a line. The log periodic will almost look like a triangle in the
same way. Each element considerably smaller and may be pointed
forward to form 'V' shaped elements.

Well then it would appear the antenna in question is probably a log
periodic then :-)

I will get myself a standard 75-300 ohm balun and see what I can do.

As for FM traps etc, no there's nothing like that. It's possible it's
not optimised for the FM band though, although it certainly is for
slightly higher VHF transmissions.