Advanced Electromagnetics (E-Journal)
Not a member yet
299 research outputs found
Sort by
Efficient methods for macroscopic magnetization simulation described by the assembly of simplified domain structure models
No full textThis article presents two methods for the fast computation of macroscopic magnetization model called assembled domain structure model. First, an efficient method for computing the demagnetizing field is proposed. Secondly, a direct searching method of equilibrium point is developed, which greatly reduces the computation time
Radiation Characteristics Enhancement of Dielectric Resonator Antenna Using Solid/Discrete Dielectric Lenses
No full textThe radiation characteristics of the dielectric resonator antennas (DRA) is enhanced using different types of solid and discrete dielectric lenses. One of these approaches is by loading the DRA with planar superstrate, spherical lens, or by discrete lens (transmitarray). The dimensions and dielectric constant of each lens are optimized to maximize the gain of the DRA. A comparison between the radiations characteristics of the DRA loaded with different lenses are introduced. The design of the dielectric transmitarray depends on optimizing the heights of the dielectric material of the unit cell. The optimized transmitarray achieves 7 dBi extra gain over the single DRA with preserving the circular polarization. The proposed antenna is suitable for various applications that need high gain and focused antenna beam
Dual-band Dipole Antenna for 2.45 GHz and 5.8 GHz RFID Tag Application
No full textIn this paper, a dual-band dipole antenna for passive radio frequency identification (RFID) tag application at 2.45 GHz and 5.8 GHz is designed and optimized using HFSS 13. The proposed antenna is composed of a bent microstrip patch and a coupled rectangular microstrip patch. The optimal results of this antenna are obtained by sweeping antenna parameters. Its return losses reach to -18.7732 dB and -18.2514 dB at 2.45 GHz and 5.8 GHz, respectively. The bandwidths (Return loss <=-10 dB) are 2.42~2.50 GHz and 5.77~5.82 GHz. And the relative bandwidths are 3.3% and 0.9%. It shows good impedance, gain, and radiation characteristics for both bands of interest. Besides, the input impedance of the proposed antenna may be tuned flexibly to conjugate-match to that of the IC chip
The Maxwell equations as a Bäcklund transformation
No full textBäcklund transformations (BTs) are a useful tool for integrating nonlinear partial differential equations (PDEs). However, the significance of BTs in linear problems should not be ignored. In fact, an important linear system of PDEs in Physics, namely, the Maxwell equations of Electromagnetism, may be viewed as a BT relating the wave equations for the electric and the magnetic field, these equations representing integrability conditions for solution of the Maxwell system. We examine the BT property of this system in detail, both for the vacuum case and for the case of a linear conducting medium
Application of the Mathieu’s equation for a design of a photonic crystal supporting surface electromagnetic waves
No full textNowadays, unique characteristics of surface electromagnetic waves, particularly, surface plasmons supported by a specially designed photonic crystal find numerous applications. We propose to exploit an evident analogy between such a photonic crystal and a structure with a sine-modulated refractive index. The light propagation inside the latter is described by the famous Mathieu’s differential equation. This application of the Mathieu’s equation can be useful for a design of multilayer structures, and also for fundamental understanding of electromagnetic phenomena in inhomogeneous media
Nano-Dielectric Resonator Antenna Reflectarray/Transmittarray for Terahertz Applications
No full textNanoantennas have introduced wide bandwidth for fast data communications. The material properties of good conducting metals introduce plasmonic behavior at Terahertz frequencies. The material property of good conducting metals using Drude Lorentz model has been investigated. The radiation characteristics of nano-dielectric resonator antenna (NDRA) reflectarray at 633 nm have been investigated. A parametric study for the nano DRA unit cell dimensions and material has been introduced. A NDR with silver ground plane have been designed and analyzed. A nano-transmitarray unit-cell has been introduced for the analysis. A comparison between the radiation characteristics of 17×17 and 21×21 NDRA transmitarray has been given. A compromise between the nano-transmitarray size, maximum gain, and operating bandwidth is applied to Terahertz applications. The finite integral technique is used to carry a full wave analysis to design a NDRA reflectarray and a NDRA transmitarray
Time-dependent sources identification for transmission lines problems
No full textThis paper is devoted to introduce an extension to the Linear Combination of Configuration Fields (LCCF). This new numerical method was designed to compute the time profile of an electromagnetic source radiating a specified electromagnetic field in all or part of the computational domain, for a specified duration. Here, we extend this idea within the framework of a transmission lines network. The principle of the method is first validated numerically. Then we prospect the same ideas in a real-data experiment which shows that the method is ready for real-life investigations
Transfer function fitting using a continuous Ant Colony Optimization (ACO) algorithm
No full textAn original approach is proposed in order to achieve the fitting of ultra-wideband complex frequency functions, such as the complex impedances, by using the so-called ACO (Ant Colony Optimization) methods. First, we present the optimization principle of ACO, which originally was dedicated to the combinatorial problems. Further on, the extension to the continuous and mixed problems is explained in more details. The interest in this approach is proved by its ability to define practical constraints and objectives, such as minimizing the number of filters used in the model with respect to a fixed relative error. Finally, the establishment of the model for the first and second order filter types illustrates the power of the method and its interest for the time-domain electromagnetic computation
New high order FDTD method to solve EMC problems
No full textIn electromagnetic compatibility (EMC) context, we are interested in developing new ac- curate methods to solve efficiently and accurately Maxwell’s equations in the time domain. Indeed, usual methods such as FDTD or FVTD present im- portant dissipative and/or dispersive errors which prevent to obtain a good numerical approximation of the physical solution for a given industrial scene unless we use a mesh with a very small cell size. To avoid this problem, schemes like the Discontinuous Galerkin (DG) method, based on higher order spa- tial approximations, have been introduced and stud- ied on unstructured meshes. However the cost of this kind of method can become prohibitive accord- ing to the mesh used. In this paper, we first present a higher order spatial approximation method on carte- sian meshes. It is based on a finite element ap- proach and recovers at the order 1 the well-known Yee’s schema. Next, to deal with EMC problem, a non-oriented thin wire formalism is proposed for this method. Finally, several examples are given to present the benefits of this new method by compar- ison with both Yee’s schema and DG approaches
Does the electromotive force (always) represent work?
No full textIn the literature of Electromagnetism, the electromotive force of a "circuit" is often defined as work done on a unit charge during a complete tour of the latter around the circuit. We explain why this statement cannot be generally regarded as true, although it is indeed true in certain simple cases. Several examples are used to illustrate these points