A direc­tion­al anten­na or beam anten­na is an anten­na which radi­ates greater pow­er in one or more direc­tions allow­ing for increased per­for­mance on trans­mit and receive and reduced inter­fer­ence from unwant­ed sources. Direc­tion­al anten­nas like Yagi-Uda anten­nas pro­vide increased per­for­mance over dipole anten­nas when a greater con­cen­tra­tion of radi­a­tion in a cer­tain direc­tion is desired.

All prac­ti­cal anten­nas are at least some­what direc­tion­al, although usu­al­ly only the direc­tion in the plane par­al­lel to the earth is con­sid­ered, and prac­ti­cal anten­nas can eas­i­ly be omni­di­rec­tion­al in one plane.

The most com­mon types are the Yagi-Uda anten­na, the log-peri­od­ic anten­na, and the cor­ner reflec­tor, which are fre­quent­ly com­bined and com­mer­cial­ly sold as res­i­den­tial TV anten­nas. Cel­lu­lar repeaters often make use of exter­nal direc­tion­al anten­nas to give a far greater sig­nal than can be obtained on a stan­dard cell phone. Satel­lite Tele­vi­sion receivers usu­al­ly use par­a­bol­ic anten­nas.

For long and medi­um wave­length fre­quen­cies, tow­er arrays are used in most cas­es as direc­tion­al anten­nas.


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