The zone beyond the near field in front of the transducer in which signal amplitude decreases monotonically in proportion to distance from the transducer. Also called the Fraunhofer zone.
Pertains to that range of listening distances in which the predominant sounds reaching the ears are reflections from room boundaries.
The region where Antenna patterns and RCS patterns need to be measured with adequate transmission distance (in terms of wavelength) or they will not be typical of the patterns expected in typical use over long distances. Measurements made over short distances (near field) contain errors because the fields are curved rather than planar.
The situation where you are far away from a source of fields. The electric and magnetic fields are coupled together to form radiation. Often the case at radiofrequencies but not at power frequencies
Moving away from a sound source, the far field is the region in which the sound level drops 6 dB for each doubling of distance. The larger the sound source, the farther away the far field begins. When measuring loudspeakers it is necessary to be in the far field, otherwise the frequency response will be different for every measuring distance. Normally, 2 meters or more is required. See Sensitivity.
When the listener is more than twice the concerned wavelength away from the source.
The region of the field of an antenna where the radiation field predominates, and where the angular field distribution is essentially independent of the distance from the antenna. A variety of guidelines is used; for some shielding calculations, 1/6th of a wavelength has been found useful.
Further than a certain distance (approximately one-sixth of a wavelength) from an emitting source.
The electromagnetic field which exists at a distance of several wavelengths from the source of radiation.
listener is in the far field when each doubling of the distance from the source results in a reduction of 6 dB in sound level, due to the inverse-square law. The far field exists between the near field and the reverberant field and is typically from 2 to 3 times the distance between the most separated points of a speaker system that are radiating at the same frequency. For practical purposes, consider it to be the point where the reflected energy begins to dominate over the direct sound energy. Therefore, its location may vary with frequency, becoming closer to the speaker system at low frequencies or at higher frequencies if the system has excellent high-frequency dispersion, and farther away at crossover points or at frequencies where the system has limited dispersion.
The area from 3 feet away from the sound source up to the critical distance. - Category: Equipment and Gear
