Search results for "DIPOLE"
showing 10 items of 982 documents
Dual-band printed dipole antenna for Wi-Fi 802.11n applications
2010
A dual-band compact printed dipole antenna for Wi-Fi 802.11n applications in the 2.45 and 5.5 GHz bands is presented. The proposed antenna consists of two printed dipoles with the arms located onto both sides of the dielectric substrate and a bended stripline. This feed scheme makes easy the integration of the antenna with the electronic subsystem and avoids the radiation towards the device. For the design and optimisation, a specifically developed finite-difference time-domain based code is used. The antenna has then been fabricated, simulated and measured. The return losses highly match the Wi-Fi frequency specifications with a moderate gain (between 1 and 3 dBi) and efficiency better tha…
Detection of defective elements in an X band array antenna from its near field measurements
2007
An algorithm has been used to detect defective elements errors in array antennas. It has been applied to an X band slot array antenna and good results have been obtained. These have enabled the detection of errors in the manufacture process. We have used spherical near field measurements of the radiated field of the antenna. Then, once the equivalent currents are be obtained, an analysis of these results will be made in order to detect possible mistakes.
Topology driven g-factor tuning in type-II quantum dots
2017
We investigate how the voltage control of the exciton lateral dipole moment induces a transition from singly to doubly connected topology in type-II InAs/GaAsxSb1−x quantum dots. The latter causes visible Aharonov-Bohm oscillations and a change of the exciton g factor, which are modulated by the applied bias. The results are explained in the frame of realistic →k⋅→p and effective Hamiltonian models and could open a venue for new spin quantum memories beyond the InAs/GaAs realm.
Directional Second Harmonic Generation Controlled by Sub-wavelength Facets of an Organic Mesowire
2018
Directional harmonic generation is an important property characterizing the ability of nonlinear optical antennas to diffuse the signal in well-defined region of space. Herein, we show how sub-wavelength facets of an organic molecular mesowire crystal can be utilized to systematically vary the directionality of second harmonic generation (SHG) in the forward scattering geometry. We demonstrate this capability on crystalline diamonoanthraquinone (DAAQ) mesowires with subwavelength facets. We observed that the radial angles of the SHG emission can be tuned over a range of 130 degrees. This angular variation arises due to spatially distributed nonlinear dipoles in the focal volume of the excit…
Effects of Mn doping on dielectric properties of ferroelectric relaxor PLZT ceramics
2017
This work has been supported by Latvian state research program IMIS2 .
Relating magnetization, structure and rheology in ferrofluids with multi-core magnetic nanoparticles
2020
Abstract Due to their magnetic moments solubilized magnetic nanoparticles are able to spontaneously assemble into dipolar mesostructures, which affect the flow behavior. Multi-core magnetic nanoparticles developed for biomedical applications have enhanced magnetic properties and show significant magnetoviscous effect, but the quantitative interpretation of this phenomenon is incomplete. We apply rheological measurements, magnetic granulometry and dimensional scaling to show the existence of a master curve for magnetorheology of these materials. Using the developed approach the magnetoviscous effect can now be interpreted in a unified way within the stochastic chain model.
Collective hydrodynamic transport of magnetic microrollers
2021
We investigate the collective transport properties of microscopic magnetic rollers that propel close to a surface due to a circularly polarized, rotating magnetic field. The applied field exerts a torque to the particles, which induces a net rolling motion close to a surface. The collective dynamics of the particles result from the balance between magnetic dipolar interactions and hydrodynamic ones. We show that, when hydrodynamics dominate, i.e. for high particle spinning, the collective mean velocity linearly increases with the particle density. In this regime we analyse the clustering kinetics, and find that hydrodynamic interactions between the anisotropic, elongated particles, induce p…
Dynamical Stark Effect in the nu(2)/nu(4) Vibrational Polyad of SiH(4): Theory and Observation.
2000
We report a theoretical and experimental investigation of the dynamical Stark effect in a tetrahedral molecule, silane (SiH(4)). We use a tetrahedral formalism and Floquet theory to calculate the absorption spectra for the molecule dressed by an intense nonresonant pulsed laser. Experimentally, the dynamical Stark effect is observed for transitions of the nu(2)/nu(4) vibrational polyad of SiH(4) by means of nanosecond diode laser absorption spectroscopy and a Nd:YAG laser excitation. Copyright 2000 Academic Press.
Dielectric Relaxation of a Polybutadiene Melt at a Crystalline Graphite Surface: Atomistic Molecular Dynamics Simulations
2014
Dielectric experiments are an indispensable tool to further our understanding of the relaxation behavior of polymers, not only in bulk samples but also in confined situations. A chemically realistic Molecular Dynamics simulation, in which all information about molecular motions is available, can shed light onto the questions of heterogeneity and anisotropy of the underlying molecular relaxation processes which lead to the ensemble averaged experimental dielectric signal. In this contribution, we present a careful analysis of the dielectric response of a weakly polar and confined polymer, 1,4-polybutadiene between graphite walls. The relaxation of the segmental dipole moments was obtained in…
Stability of electrically conducting liquid flow driven by a rotating magnetic dipole in a ring channel
2020
The stability of electrically conducting liquid flow in a cylindrical ring channel is studied numerically. The flow is driven by a rotating magnetic dipole placed at the ring’s center. Depending on ring’s width, two distinct flow regimes are observed. In a narrow ring, the flow itself and its instability resemble the related rotating magnetic field driven flow in a cylinder. This changes in a wide ring when an intense radial jet develops on the midplane. Within this jet, the driving magnetic force is overwhelmed by inertial and viscous forces similar to how it occurs in the boundary layer flow. The instability develops as an azimuthally periodic wave-like deformation of this jet. Non-unifor…