In message , Jeff writes

I think we refer to "beam antennas" that way because they behave like
lamps with reflectors, directing a beam of RF like a beam of light. I
don’t know the historical accuracy of my thinking.



I think from a historical perspective the name derives from 'Beam
Stations' such as those comprised in the Imperial Wireless Chain. That
is stations that were set up to 'beam' their signals to far flung
places on the globe.

Antennas were not what would be described as beam antennas these days
but were types such as curtain arrays.

Jeff

Surely the term "beam" is generic? I would have thought that any antenna
or antenna system which is deliberately designed to concentrate its
radiation or reception would qualify to be called thus.
--
Ian