Directivity Factor definition of Directivity Factor in the Free Online Encyclopedia.

directivity factor [də‚rek′tiv·əd·ə ‚fak·tər]

(engineering acoustics)

The ratio of radiated sound intensity at a remote point on the principal axis of a loudspeaker or other transducer, to the average intensity of the sound transmitted through a sphere passing through the remote point and concentric with the transducer; the frequency must be stated.

The ratio of the square of the voltage produced by sound waves arriving parallel to the principal axis of a microphone or other receiving transducer, to the mean square of the voltage that would be produced if sound waves having the same frequency and mean-square pressure were arriving simultaneously from all directions with random phase; the frequency must be stated.

Directivity Factor

(1) For a transmitting antenna, a number indicating the factor by which the radiated power would have to be increased if the antenna were replaced by an isotropic radiator (assuming the same field intensity for the antenna and the isotropic radiator).

(2) For a receiving antenna, a number indicating the factor by which the input power of the receiver for the direction of maximum reception exceeds the mean power obtained by averaging the power received from all directions of reception (if the field intensity at the antenna location is equal for any direction of wave incidence).

The directivity factor is a quantitative characterization of the capacity of a transmitting antenna to concentrate the radiated energy in a given direction or the capacity of a receiving antenna to select signals incident from a given direction.

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