What sort of antenna offers narrow beamwidth, combined with smooth
sidelobes?
I'm not too concerned with F/B ratio, or the magnitude of the sidelobes,
(smaller is better obviously) but I'm more concerned that they not be a mess
of deep spiky notches.

This is a somewhat special application above the 440 band, but I could scale
a 440/900/1296 design appropriately. Gain, per se, isn't really an issue,
and negative gain may in fact be acceptable.

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