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.
Papers published on a yearly basis
Papers
More filters
TL;DR: In this article, a fine open-ended coaxial probe above an operating microwave device was used to image local electric fields generated by the device at microwave frequencies, where the probe is sensitive to the electric flux normal to the face of its center conductor, allowing different components of the field to be imaged by orienting the probe appropriately.
Abstract: By scanning a fine open-ended coaxial probe above an operating microwave device, we image local electric fields generated by the device at microwave frequencies. The probe is sensitive to the electric flux normal to the face of its center conductor, allowing different components of the field to be imaged by orienting the probe appropriately. Using a simple model of the microscope, we are able to interpret the system's output and determine the magnitude of the electric field at the probe tip. We show images of electric field components above a copper microstrip transmission line driven at 8 GHz, with a spatial resolution of approximately 200 $\mu$m.
51 citations
TL;DR: In this article, the authors illustrate the ability of electrooptic sensors to perform electric (E)-field vectorial measurements, and demonstrate the use of such a technology for electrical equipment and energy line monitoring.
Abstract: In this paper we illustrate the ability of electrooptic sensors to perform electric (E)-field vectorial measurements. Thanks to their frequency response spreading over nine decades and to their measurement dynamics reaching 120 dB, these sensors are of high interest for some applications (near field mapping, energy line monitoring, electromagnetic compatibility, and so on). Furthermore, due to their fully dielectric structure and millimetric size, almost no perturbation is induced on the E-field to be measured, even in the near field region. This paper is focused on high-intensity pulsed E-field characterization in different environments such as air, water (bioelectromagnetism applications), or plasmas ( in situ assessment of the E-field associated to an electric discharge and to the induced plasma). The use of such a technology for electrical equipment and energy line monitoring is also investigated.
51 citations
01 Jan 2007
TL;DR: In this article, two-dimensional laser Rayleigh measurements of thermal gradient structures are performed in a turbulent non-premixed jet flame, where the measurements focus on the near field (10 nozzle diameters downstream of the jet exit) where traditional scaling laws from the self-similar far field of nonreacting jets are not necessarily applicable.
Abstract: Two-dimensional laser Rayleigh measurements of thermal gradient structures are performed in a turbulent non-premixed jet flame. The measurements focus on the near field (10 nozzle diameters downstream of the jet exit) where traditional scaling laws from the self-similar far field of non-reacting jets are not necessarily applicable. The optical performance of the high-resolution imaging system is characterized. The square of the temperature gradient field is analyzed by calculating the power spectral density (PSD) and by directly measuring the thicknesses of the layer-like structures. Fully resolved spectra extending over three orders of magnitude in PSD are obtained using a new noise cancellation technique. Some spatial filtering (smoothing) is necessary to reliably measure the layer-normal structure widths in the images. The probability density function (PDF) of the layer widths is found to be approximately log-normal. The PDFs of the 20-percent-full-width layer thicknesses have peak values at 216 and 368 μm for r/d = 0 and r/d = 1, respectively. The peak of the layer-thickness probability density function (PDF) occurs at a length scale where the PSD is at approximately 0.5 percent of its maximum in both the low-temperature centerline region and the region near the maximum mean temperature.
51 citations
TL;DR: In this article, surface integral representations for electromagnetic wave scattering from dielectric bodies are derived, and the interior resonant solutions, the cause of erroneous solutions, accompanied with the equations presented here and the removal of these solutions are briefly discussed.
Abstract: The surface integral representations are derived for electromagnetic wave scattering from dielectric bodies. Several kinds of integral equations are given for dielectric cylinders immersed in an obliquely incident wave. The interior resonant solutions, the cause of erroneous solutions, accompanied with the equations presented here and the removal of these solutions are briefly discussed.
51 citations
TL;DR: In this article, a tip-enhanced near field Raman microscope was developed that can precisely regulate longitudinal distance between a metallic tip and sample molecules by employing a time-gated photoncounting scheme.
Abstract: The authors developed a tip-enhanced near field Raman microscope that can precisely regulate longitudinal distance between a metallic tip and sample molecules. This was done by employing a time-gated photoncounting scheme that enabled us to observe exponentially decaying near field Raman intensity with the tip-sample distance. The exponential decay shows a characteristic of the enhanced field generated by the localization of the surface plasmon polaritons near the tip apex. This microscope was applied to evaluate metal-coated tips and also to investigate confinement of the field generated at a gap between two metal nanostructures from the decay curves.
51 citations