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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 ...
Scanning near-field ultrasound holography combines atomic force acoustic microscopy and ultrasonic force microscopy. Two transducers producing high frequencies are used. Usually frequency is higher than the resonant frequency of the cantilever. One transducer is placed below the sample and the other attached to the cantilever.
The general idea of acoustic holography has led to advanced processing methods such as statistically optimal near-field acoustic holography (SONAH). [4] For audio rendering and production, Wave field synthesis and higher-order Ambisonics are related technologies, respectively modeling the acoustic pressure field on a plane, or in a spherical ...
Sound field of a non focusing 4 MHz ultrasonic transducer with a near field length of N = 67 mm in water. The plot shows the sound pressure at a logarithmic db-scale. Sound pressure field of the same ultrasonic transducer (4 MHz, N = 67 mm) with the transducer surface having a spherical curvature with the curvature radius R = 30 mm
Evanescent-wave coupling is synonymous with near field interaction in electromagnetic field theory. Depending on the nature of the source element, the evanescent field involved is either predominantly electric (capacitive) or magnetic (inductive), unlike (propagating) waves in the far field where these components are connected (identical phase ...
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.
Google aims to release commercial quantum computing applications within five years, Google's head of quantum told Reuters on Wednesday, in a challenge to Nvidia's predictions of a 20-year wait.
The near field can be specified by the Fresnel number, F, of the optical arrangement. When F ≪ 1 {\displaystyle F\ll 1} the diffracted wave is considered to be in the Fraunhofer field. However, the validity of the Fresnel diffraction integral is deduced by the approximations derived below.