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The near field refers to places nearby the antenna conductors, or inside any polarizable media surrounding it, where the generation and emission of electromagnetic waves can be interfered with while the field lines remain electrically attached to the antenna, hence absorption of radiation in the near field by adjacent conducting objects detectably affects the loading on the signal generator ...
Studio monitor Little Gold Monitor (c. 1990) from Tannoy with two-way-coaxial construction, meaning the tweeter for frequencies from 1.400 Hz and above is located independently in the center of the 30 cm bass driver Tannoy, Dynaudio, Genelec, and K+H studio monitors. By the mid-1980s the near-field monitor had become a permanent fixture.
The first technique developed was the far-field range, where the antenna under test (AUT) is placed in the far-field of a range antenna. Due to the size required to create a far-field range for large antennas, near-field techniques were developed, which allow the measurement of the field on a distance close to the antenna (typically 3 to 10 ...
The far-field pattern of an antenna may be determined experimentally at an antenna range, or alternatively, the near-field pattern may be found using a near-field scanner, and the radiation pattern deduced from it by computation. [1] The far-field radiation pattern can also be calculated from the antenna shape by computer programs such as NEC.
Using near-field optical techniques, researchers currently resolve features in the order of tens of nanometers in size. While other imaging techniques (e.g. atomic force microscopy and electron microscopy) can resolve features of much smaller size, the many advantages of optical microscopy make near-field optics a field of considerable interest.
In current commercial implementations of near-field communications, the most commonly used carrier frequency is 13.56 MHz and has a wavelength (λ) of 22.1 meters. The crossover point between near-field and far-field occurs at approximately λ/2π. At this frequency the crossover occurs at 3.52 meters, at which point the propagating energy from ...
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As the distance from the antenna increases, the EH phase difference decreases. Far from a small antenna in the far-field, the EH phase difference goes to zero. [2] Thus a receiver that can separately measure the electric and magnetic field components of a near-field signal and compare their phases can measure the range to the transmitter. [3]