Guideline factor

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The directivity factor generally expresses that a radiated power is concentrated on a certain part of the room and the radiation is not homogeneous . It is used in various areas such as sound engineering or antenna technology.

Areas of application

Sound engineering

In sound engineering, the directivity factor characterizes the spatial sensitivity of a sound-absorbing system such as a microphone or a sound-emitting system such as a loudspeaker . It indicates the ratio with which the sound pressure level or the sound pressure averaged over all directions of the full space is reproduced weaker than on the 0 ° main axis of the system.

In the case of an ideal spherical radiator , the directivity factor is 1, since the microphone and loudspeaker are equally sensitive in all spatial directions.

See also Statistical Directivity .

Antenna technology

In the context of antenna technology, the directivity factor D is the ratio of the radiation density of a certain antenna in the main radiation direction in relation to the radiation density of a spherical radiator in electromagnetic waves . The directivity factor is an essential part of the antenna gain.


  • Gregor Häberle, Heinz Häberle, Thomas Kleiber: Expertise in radio, television and radio electronics. 3rd edition, Verlag Europa-Lehrmittel, Haan-Gruiten, 1996, ISBN 3-8085-3263-7
  • Helmut Röder, Heinz Ruckriegel, Heinz Häberle: Communication electronics . Radio and television electronics (= electronics. Vol. 3). 5th edition. Verlag Europa-Lehrmittel, Wuppertal 1980, ISBN 3-8085-3225-4 .