From AMS Glossary
(Often called yagi antenna.) A type of directional antenna comprising an elevated linear array of horizontal dipoles with different lengths and spacings, typically arranged as a driven element, reflector element, and several director elements.
The dipoles are organized to maximize the radiation in the forward direction. Radar systems requiring large antennas often use arrays of Yagi-Uda antennas (e.g., some wind profiler radars).