Numerical simulation of the frequency response and phase response of combined UWB antennas in the receiving-transmitting mode

Results of a simulation and experimental study of a combined ultra-wideband antenna, which is a combination of electric and magnetic dipoles, are presented. The input signal recovery of the transceiver path of combined antennas made by the MathCad code and the experimental one were compared. The reconstruction took place according to the frequency and phase responses of the transceiver path of these antennas.

Intrinsic Topological Magnons In Arrays of Magnetic Dipoles

We study a simple magnetic system composed of periodically modulated magnetic dipoles with an easy axis. Upon adjusting the modulation amplitude alone, chains and two-dimensional stacked chains exhibit a rich magnon spectrum where frequency gaps and magnon speeds are easily manipulable. The blend of anisotropy due to dipolar interactions between magnets and geometrical modulation induces a magnetic phase with fractional Zak number in infinite chains and end states in open one-dimensional systems. In two dimensions it gives rise to topological modes at the edges of stripes. Tuning the amplitude in two-dimensional lattices causes a band touching, which triggers the exchange of the Chern numbers of the volume bands and switches the sign of the thermal conductivity.

Physical Mechanisms of Magnetic Field Effects on the Dielectric Function of Hybrid Magnetorheological Suspensions

In this paper, we study the electrical properties of new hybrid magnetorheological suspensions (hMRSs) and propose a theoretical model to explain the dependence of the electric capacitance on the iron volumetric fraction, ΦFe, of the dopants and on the external magnetic field. The hMRSs, with dimensions of 30 mm×30 mm×2 mm, were manufactured based on impregnating cotton fabric, during heating, with three solutions of iron microparticles in silicone oil. Flat capacitors based on these hMRSs were then produced. The time variation of the electric capacitance of the capacitors was measured in the presence and absence of a magnetic field, B, in a time interval of 300 s, with Δt=1 s steps. It was shown that for specific values of ΦFe and B, the coupling coefficient between the cotton fibers and the magnetic dipoles had values corresponding to very stable electrical capacitance. Using magnetic dipole approximation, the mechanisms underlying the observed phenomena can be described if the hMRSs are considered continuous media.

A Model of Two Quantum Fluids for the Low Energy Excited States of the Systems with Entities That Mimic the Magnetic Monopoles

The low energy excitation states in frustrated magnetic structures can generate quasiparticles that behave as if they were magnetic charges. These excited states produce, in the so-called spin-ice materials, two different peaks of specific heat at temperatures less than 1.5 K. In this paper, we consider that the first structure is caused by the formation of fluid of magnetic dipoles configured by the dumbbell model with a boson nature in consonance with that described by Witten for mesons. The second structure, wider than the first one, corresponds to a plasma state that comes from the breaking of a great number of dipoles, which provokes the appearance of free magnetic charges, which constitute a cool magnetic plasma fluid. In this paper, we determine thermodynamic analytical functions: the thermo-potential and internal energy and their respective derivative physical magnitudes: entropy, and magnetic specific heat. We obtain results in a good concordance with the experimental data, which allow us to explain the phase transitions occurred in these spin-ice materials at very low temperatures.

Generation and collective interaction of giant magnetic dipoles in laser cluster plasma

Interaction of circularly polarized laser pulses with spherical nano-droplets generates nanometer-size magnets with lifetime on the order of hundreds of femtoseconds. Such magnetic dipoles are close enough in a cluster target and magnetic interaction takes place. We investigate such system of several magnetic dipoles and describe their rotation in the framework of Lagrangian formalism. The semi-analytical results are compared to particle-in-cell simulations, which confirm the theoretically obtained terrahertz frequency of the dipole oscillation.

An Electromagnetic Cloaking Scheme Using Magnetic Dipole Based Scattering Cancellation

This paper explores the possibility of creating a cylindrical electromagnetic cloaking scheme using resonant magnetic dipole excitation. Split-ring resonators are arranged around the cylindrical metal target to generate strong subwavelength resonant magnetic dipole moments to cancel far-field scattered power from the target. We used the multipole scattering theory to identify the actual reason behind scattering cancellation. The scattering from resonant circulating magnetic dipoles interferes destructively with that from the non-resonant electric dipole moments of the target resulting in a significant reduction in the Scattering Cross Section. The results are verified using full-wave simulation software and subsequently validated with backscattering measurements inside an anechoic chamber.

Calculation apparatus for modeling the distribution of electromagnetic fields of different sources

The calculation apparatus acceptable for assumptions and simplifications and sufficient for errors of final results for modeling the propagation of electric, magnetic and electromagnetic fields spread over a certain area was proposed. It is shown that to model the propagation of ultra-low frequency electric and magnetic fields (monitors, uninterruptible power supplies, transformers, electric motors and generators) it is possible to consider these sources as dipole and dipole-quadrupole type sources. That is, the field of the local source can be considered as a combination of electric and magnetic dipoles. This makes it possible to delineate with sufficient accuracy the zones of exceeding the maximum allowable field strengths. The calculation apparatus used to determine the radiation intensities of civil aviation radar equipment was adapted to model the propagation of electromagnetic fields of very high and ultra-high frequencies. The calculations of coefficients that take into account the parameters of radiation patterns in the horizontal and vertical planes for the most common radiation sources are given. These ratios and corresponding coefficients can be used to determine the electromagnetic environment in the presence of many high-frequency sources (mobile communication base stations, navigation equipment, radio relay stations, etc.). The proposed approach allows to automate processes of designing the placement of electromagnetic, electronic and radio equipment in production areas and territories, as well as to assess the environmental impact at the stages of design work. This will make it possible to delineate the isolines of the limits of exceeding the maximum permissible levels of electric magnetic and electromagnetic fields for different frequency ranges and categories of equipment and to automatically determine the electromagnetic load at each point of the controlled space.