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Electromagnetic near-field scanner (NFS [1]) is a measurement system to determine a spatial distribution of an electrical quantity provided by a single or multiple field probes acquired in the near-field region of a device under test possibly accompanied by the associated numerical post-processing methods enabling a conversion of the measured quantity into electromagnetic field.
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 ...
Planar near-field measurements are conducted by scanning a small probe antenna over a planar surface. These measurements are then transformed to the far-field by use of a Fourier transform, or more specifically by applying a method known as stationary phase [2] to the Laplace transform. Three basic types of planar scans exist in near field ...
Near field infrared spectrometry and near-field dielectric microscopy [19] use near-field probes to combine sub-micron microscopy with localized IR spectroscopy. [ 25 ] The nano-FTIR [ 26 ] method is a broadband nanoscale spectroscopy that combines apertureless NSOM with broadband illumination and FTIR detection to obtain a complete infrared ...
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.
E-field projections on an orthogonal reference frame. Measurements of the EMF are obtained using an E-field sensor or H-field sensor which can be isotropic or mono-axial, active or passive. A mono-axial, omnidirectional probe is a device which senses the Electric (short dipole) or Magnetic field linearly polarized in a given direction.
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.
Near-field electromagnetic ranging is an emerging RTLS technology that employs transmitter tags and one or more receiving units. Operating within a half- wavelength of a receiver, transmitter tags must use relatively low frequencies (less than 30 M Hz ) to achieve significant ranging.