Roy Lewallen wrote:
I'm not sure I understand the question, but a large fraction of the
total power is typically in the main lobe of a Yagi. You won't increase
the power in the main lobe significantly by reducing or eliminating
other lobes, because there just isn't much power there.

Roy you know better than that ! gain is a binomial function with
respect
to the forward radiation at the point of initiation. It does nothing to
salvalge energy
expended in the reaward direction, to do that another vector is
required that cannot be produced by a planar array. As far as traps
being lossy as if they get hot or something that is also untrue, what
you are seeing is a radiation field created by the trap that is in
opposition to that created on the element i.e. a field that is 180
degrees out of phase



If you want more
power in a narrower range of directions, you need more directionality,
which means a longer Yagi, stacked Yagis, or some other type of antenna
which will probably be larger. The methodology for and tradeoffs
involved in increasing directionality are well known.

And because Yagis
(ones not having lossy traps or loading components) are very efficient,
directionality and gain are inextricably linked. Again I do not agree that Yagis are efficient

Art

Roy Lewallen, W7EL