The multiband, Yagi-Uda array may well be evolving towards trapless designs,
with coaxial coupled, indirectly driven radiators, interlaced elements, and
which will be more efficient, broader banded and lighter weight... This is
most welcome if it all works out... But in our blue sky dreaming we need to
keep sight of the fact that the far field patterns of parasitic antennas were
well worked out by Drs. Yagi and Uda, refined by other workers since then,
and codified in the NEC; and that gain is dependent upon the boomlength as
expressed in lambda (wavelength)... For those running about proclaiming that
beam A has equal performance to beam B which has a boom length 178% that of
A, because beam A is more efficient and has more elements, need to improve
their bedtime reading list ...
As far as sneering at a 1dB increased gain (estimated) for the longer boom
antenna as discussed recently, I would suggest that you remember the comment
by one of our contestors who, when his wife asked, "What is a dB?", replied -
"About $1500 at this station"...