nbr wrote:
Why is the horizontal sengment of a 1/2-square
considered a "phasing line" and not a radiator?

The center of the "phasing line" on a half-square is a
maximum voltage point but there is nothing to keep that
horizontal wire from radiating. At a TOA of about 65 degrees
the broadside horizontal radiation and vertical radiation of
a half-square are about equal at about -9 dBi.
--
73, Cecil, W5DXP