beamwidth an power reveived of antenna

[hogmeade]

For a short linear antenna (l<< lama) the received power increases in direct proportion to the length of the antenna?
The higher the directivity of an antenna the wilder the beamwidth? Anyone has equation o prove these?
Thank you so much.

 

[juppydu]

exactly the opposite : high gain small beamwidth and viceversa. The bigger is the antenna the bigger is the gain