Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 23 for “"far-field radiation"”.
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An Improved dipole-moment model based on near-field scanning for characterizing near-field coupling and far-field radiation from an IC
… IC radiated emission model based on near-field measurements is proposed. The regularization technique and the truncated SVD method are employed together with the least square method to calculate the dipole moments from the near-field data. This dipole model has clear physical meaning: the …
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Spherical antenna array
"The far field radiation pattern of an isotropic spherical antenna array with two types of element distributions, a latitude-longitude distribution and an approximately equally-spaced distribution, has been analyzed using Poisson's Sum Formula. Beamwidth expressions of both element distributions …
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New Approach to finding Active Element Patterns for Large Arrays
… infinite array and a summation is done for the far-field radiation values of a finite array based on the number of elements using typical pattern multiplication techniques. Therefore, accuracy of the Floquet element approach is excellent for arrays on the size of hundreds to thousands of …
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Performance characteristics on patch antenna with sar reduction using artificial magnetic conductor (amc) for wban applications
… achieved narrow bandwidth, decrease gain, low radiation efficiency, a high specific absorption rate (SAR) value, high front-to-back ratio (FBR) and structural complexity. However, it is necessary to achieve better performance antenna for less impact of frequency detuning, by improving FBR, high …
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Impact of ground plane serrations on radiation and impedance characteristics of a slot antenna over a conductive back plane
… across many design variations. Finally, the far-field radiation is investigated to shed light on the underlying mechanisms affecting impedance.
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Surface phonon polaritons coupled to the far-field by a grating at high temperature
… polaritons (SPhP) in quartz coupled to the far field by gratings, and the temperature dependence of SPhP coupled to the far field. The subject of coupling SPhP to the far-field has been studied in the past, but not at high temperature. Devices proposed to control radiative heat transfer …
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Computation of acoustic scattering from elastic conical shells with endcaps using the hybrid finite element/ virtual source approach
… is being insonified. Accurate results for the far-field radiation of the target can be obtained by superposition of the point source Green's function of each virtual source. The hybrid virtual source/FE approach shows potential to be a computationally efficient method for computing acoustic …
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Emission source microscopy for electromagnetic interference source localization
… it is often difficult to localize the sources of radiation. Near-field electromagnetic scanning is used often for root-cause diagnosis by determining field distribution close to the PCB. In the near-field, the evanescent waves are dominant, which may lead to the misinterpretation of them being the …
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Near-field scanning study for radio frequency interference estimation
… discusses the novel techniques using near-fields scanning to do radio frequency interference (RFI) estimation. As the electronic products are becoming more and more complicated, the radio frequency (RF) receiver in the system is very likely interfered by multiple noise sources …
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Characteristics of defect modes, slow light, and disorder in photonic crystals
… 2D photonic crystals in terms of polarization, field profile, and projected band structures. The results should facilitate the implementation of 2D photonic-crystal devices in realistic 3D systems. Chapter 3 explores the possibility of using photonic-crystal defect modes to design magnetic …
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Control and in-situ measurement of adaptive and reconfigurable RF systems.
… measurements also enable the prediction of far-field radiation patterns.
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Helical Antenna Optimization Using Genetic Algorithms
… on the Virginia Tech outdoor antenna range. Far-field radiation patterns are measured over a wide frequency range. The axial-ratio information is extracted from the measured pattern data. Comparison of measured and NEC-2 computed radiation patterns shows excellent agreement. The agreement …
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Reduced fan noise radiation from a supersonic inlet
… designed to reduce flow distortion and noise radiation. The new door geometry uses door passages with increased circumferential span to improve the distribution of the flow entering through the doors. In addition, the new design employs sonic flow velocity at the inlet throat and a converging …
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A computational and experimental investigation into the aeroacoustics of low speed flows
… the understanding of noise generation and far field radiation. Numerical simulations are performed to investigate the tonal noise radiated by two- and three-dimensional cavities submerged in low-speed turbulent and laminar flows. A numerical approach is developed that combines near field …
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Low-power dual-band on-body antenna for wireless body sensor networks
… to the human body is developed and the radiated fields from the proposed on-body antennas in the near zone are evaluated.The commercially available CST® simulator is used and experimental measurements are done for the five fabricated prototypes. The near-field distribution over the surface of …
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Optical bound states in the radiation continuum : from topological charges to light-emission applications
… a general class of geometries where all of its radiation amplitudes vanish simultaneously due to destructive interference. Finally, we provide a fundamental understanding about the nature of BICs that unify both types of BICs. We also explain the robustness of them through their topological …
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Bridging conduction and radiation : investigating thermal transport in nanoscale gaps
Near field radiation transfer between objects separated by small gaps is a widely studied field in heat transfer and has become more important than ever. Many technologies such as heat assisted magnetic recording, aerogels, and composite materials with interfacial transport involve heat transfer …
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Modelling and analysis of complex electromagnetic problems using FDTD subgridding in hybrid computational methods. Development of hybridised Method of Moments, Finite-Difference Time-Domain method and subgridded Finite-Difference Time-Domain method for precise computation of electromagnetic interaction with arbitrarily complex geometries
… interest, particularly the pipeline. The induced fields above the pipeline are investigated and analysed. FDTD is based on the solution of Maxwell¿s equations in differential form. It is very useful for modelling complex, inhomogeneous structures. Problems arise when open-region geometries are …
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Modal and radiation characteristics of the crossed-septum dielectric loaded waveguide for wideband applications
… the modal symmetry properties of the electric field about a given axis within the guide. The objective is to increase the modal separation between the TE<sub>10</sub> (or TE<sub>01</sub>) mode having even/odd (or odd/even) symmetry and TE,, mode having odd/odd symmetry in the guide. The …
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Reconfigurable phased microstrip antenna array with defected ground structure and defected microstrip structure for beam steering application
… steer the beam maximum of an antenna electric field pattern to some predefined point in space. The performance of a phased antenna array for beam steering without moving the antennas is important to military and civil applications. A steerable antenna with tunable phase shifter continues to be …
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