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: In this article, a procedure for the calibration and compensation of near-field scanning is described and demonstrated, where the objective is to quantify the individual field components associated with electromagnetic interference (EMI) from high speed circuitry and devices.
Abstract: A procedure for the calibration and compensation of near-field scanning is described and demonstrated. Ultimately, the objective is to quantify the individual field components associated with electromagnetic interference (EMI) from high speed circuitry and devices. Specific examples of these methods are shown. The effects of compensation are small but noticeable when the uncompensated output signal from near field scanning is already a very good representation of the field being measured. In other cases, the improvement provided by compensation can be significant when the uncompensated output signal bears little resemblance to the underlying field.
62 citations
TL;DR: In this paper, the authors observed transmitted signals of phase change marks recorded in super-resolution near-field structure (super-RENS) disks under high speed disk rotation, and the observed minimum mark size was 81 nm and the carrier to noise ratio was about 6 dB at a constant linear velocity of 4.8 m/s.
Abstract: We observed transmitted signals of phase change marks recorded in super-resolution near-field structure (super-RENS) disks under high speed disk rotation. The observed minimum mark size was 81 nm and the carrier to noise ratio was about 6 dB at a constant linear velocity of 4.8 m/s. The mark size was far beyond the diffraction limit of an optical pickup with a wavelength of 635 nm and a numerical aperture of 0.6. It was clear that near-field scattering actually occurred in super-RENS disks.
62 citations
Book•
01 Sep 1971
TL;DR: In this article, fundamenlals of transmission lines and electromagnetic fields are used to calculate the distance between transmission line and electromagnetic field, where the distance is expressed as a function of the distance from the transmitter to the receiver.
Abstract: Fundamenlals of transmission lines and electromagnetic fields , Fundamenlals of transmission lines and electromagnetic fields , کتابخانه دیجیتالی دانشگاه علوم پزشکی و خدمات درمانی شهید بهشتی
62 citations
TL;DR: In this paper, the authors proposed a finite-difference time-domain (FDTD) technique for the analysis of radio wave scattering from geophysical surfaces, where the average surface is modelled as a flat, homogeneous half-space.
Abstract: A major difficulty in physical interpretation of radio wave scattering from geophysical surfaces is the lack of detailed information on the signatures of geologically plausible discrete objects. Although the aggregate response will never be dominated by any single object, differences in the population of discrete objects on or near the surface (their sizes and shapes, for example) can change the character of a radio echo markedly. When the average surface is modelled as a flat, homogeneous half-space, the field that "drives" the scattering process is a composite consisting of the incident plane wave and the reflected and transmitted plane waves, all of which are known quantities; the total field can then be defined as the sum of the driving field and the scattered field. When a discrete object is near the surface, the total field can be calculated using finite-difference time-domain (FDTD) techniques, and the scattered near field can be calculated accordingly. The Green's functions for electric and magnetic currents above and below the surface, obtained by Sommerfeld theory and employed in conjunction with Huygens' principle, transform the local scattered fields to the far field. The FDTD implementation accommodates discrete lossy dielectric and magnetic scatterers in the vicinity of a dielectric surface; extension to a lossy half-space is straightforward. Two-dimensional results for scattering from perfectly conducting circular cylinders above and below a dielectric surface agree with moment method solutions within a few percent. Results for scattering from a dielectric wedge exhibit expected forward diffraction and internal reflection phenomena.
62 citations
TL;DR: It is shown that the intensity in a grating's near field can be enhanced significantly compared with conventional interferometric lithography, and predicted that high-intensity, high-contrast patterns with 135-nm period can be formed in photoresists more than 50 nm thick.
Abstract: Simulation results are presented to illustrate the main features of what we believe is a new photolithographic technique, evanescent interferometric lithography (EIL). The technique exploits interference between resonantly enhanced, evanescently decaying diffracted orders to create a frequency-doubled intensity pattern in the near field of a metallic diffraction grating. It is shown that the intensity in a grating’s near field can be enhanced significantly compared with conventional interferometric lithography. Contrast in the interference pattern is also increased, owing to a reduction in the zeroth-order transmission near resonance. The pattern’s depth of field reduces as the wavelength is increased beyond cutoff of the first-order diffracted components, and results are presented showing the trade-offs that can be made between depth of field and intensity enhancement. Examples are given for a 270-nm-period grating embedded in material with refractive index n = 1.6 and illuminated with wavelengths near 450 nm. Under these conditions it is predicted that high-intensity, high-contrast patterns with 135-nm period can be formed in photoresists more than 50 nm thick.
62 citations