Topic
Near and far field
About: Near and far field is a research topic. Over the lifetime, 15922 publications have been published within this topic receiving 220571 citations.
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TL;DR: Theoretical expressions for the incident and scattered field from a rigid immovable sphere are derived in this paper, where the near and far-field acoustic scattering fields are expressed using partial wave series involving the spherical harmonics, the scattering coefficients of the sphere, the half-conical angle of the wave number components of the beam, its order and the beam shape coefficients.
63 citations
TL;DR: In this paper, the authors describe a technique for the measurement of the electric near field at the package surface of microprocessors and other VLSI devices using precision stepper motors for highly accurate placement of an electric field probe at the surface of the device.
Abstract: This short paper describes a technique for the measurement of the electric near field at the package surface of microprocessors and other VLSI devices. The technique uses precision stepper motors for highly accurate placement of an electric field probe at the surface of the device to be measured. Structural resolution across the device is on the order of 400-600 /spl mu/m. Typical scans accumulate 10000 data points across a variable scan area, which can be defined by device package dimensions or by the die dimensions. Characterizing a device involves a repeated series of surface scans at harmonics of the fundamental clock frequency. This paper describes the electric near field at the surface of a multichip module (MCM) composed of a processor, a flash memory, and application specific integrated circuit (ASIC). The MCM was measured while in operation in the actual circuit application.
63 citations
TL;DR: In this article, it was shown that surface polaritons can be effectively launched at the edges of a metal film illuminated at an angle of incidence greater than the resonant angle of surface polariton excitation.
Abstract: Nonresonant excitation of surface plasmon polaritons at discontinuities of a gold film is numerically studied and experimentally observed with scanning near-field optical microscopy. It is shown that surface polaritons can be effectively launched at the edges of a metal film illuminated at an angle of incidence greater than the resonant angle of surface polariton excitation. The electromagnetic near-field distribution over a thin metal film exhibits significantly different features under resonant and nonresonant excitations due to different surface polariton excitation mechanisms. In the latter case the field distribution is determined by the interference of the excitation light and surface polaritons launched on air-metal and glass-metal interfaces. In the former case the interference of surface polariton modes excited on different interfaces of a metal film is dominating. The modulation depths of the respective interference patterns correspond to the efficiency of the intensity conversion of the excitation light at the metal discontinuities into surface polaritons of the order of 0.1-0.01 depending on an angle of incidence.
62 citations
TL;DR: In this paper, the authors presented a detailed analysis of a broadband (2-18 GHz) cavity-backed Archimedean spiral antenna using the finite-volume time-domain method.
Abstract: This paper presents a comprehensive analysis of a broadband (2-18 GHz) cavity-backed Archimedean spiral antenna. The simulation of the device is performed using the finite-volume time-domain method. The high geometrical flexibility of this method permits a detailed modeling of the antenna including the thin substrate, the feeding balun, and the cavity loaded with a honeycomb absorber. The simulated far-field radiation patterns and the return loss are compared to measurements, showing an excellent agreement over the whole frequency band. The radiation mechanism of the spiral is visualized by observing the current distribution on the spiral arms for both pulsed and harmonic excitation modes
62 citations
TL;DR: In this paper, a tungsten tip is used to perturb locally and periodically the electromagnetic field in the diffraction limited spot and the vibration amplitude is kept at a constant value when scanning the sample.
62 citations