Tom, K0TAR wrote:
"What I meant was, none of the elements of a yagi are resonant, except
perhaps the driven element."

That`s usually right. The reflector is lengthened and directors are
shortened to conveniently produce phase relations which determine
reinforcement or repression in directions as desired.

However, this is not the only way. Commercial broadcast curtain antenna
arrays use parasitic elements which have the same length as the driven
elements in some instances. Short-circuit stubs repalace drive lines in
the parasitic elements, and these are adjusted for the desired phasing
instead of adjusting element lengths.

Best regards, Richard Harrison, KB5WZI