From AMS Glossary
A type of radar antenna that forms a beam having a greater beam width in azimuth than in elevation, or vice versa.
In physical dimensions, its long axis lies in the plane of smaller beam width. A beam that is wide in azimuth angle and narrow in elevation angle is employed on height-finding radars. Search radars usually have beams narrow in azimuth but broad in elevation angle. In general, the narrower the beam, the greater the angular resolution.