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Numerical simulation of electromagnetic models with multiscale features is highly challenging due to the fact that electrically large as well as small features are simultaneously present in the model, which in turn requires that the computational domain be discretized such that the number of degrees of freedom (DOF) is very large and hence, levies a heavy burden on computational resources.
Despite the availability of modern supercomputers, direct solution of multiscale problems by means of conventional CEM methods-be it FEM, FDTD or MoM-is highly challenging. This is because modeling of structures with fine features, which might share the computational domain with other large objects, often requires dealing with a large number of degrees of freedom. Dealing with such multiscale problems...
In a typical Logging While Drilling (LWD) application, several coils operating in the frequency range of few KHz to MHz are used as transmitters and receivers to characterize the earth formation. Electromagnetic modeling of such a low frequency system poses serious computational challenges. In the Method of Moment (MoM) formulation, contribution of vector potential to the total field becomes several...
In this paper we introduce a universal Method of Moment (MoM)-based formulation, which overcomes some of the drawbacks of conventional frequency domain techniques. Formulating the problem in a way that bypasses the evaluation of the electric field as a summation of scalar and vector potential terms enables us to overcome the low-frequency breakdown when applied to the solution of the Surface Electric...
A method of moments (MoM)-based procedure is developed for efficient treatment of scattering problems over a wide frequency band where many of the conventional algorithms often fail. The proposed method uses a type of basis function whose radiated field is expressible in a convenient closed-form. This, in turn, circumvents the need to either employ the Green's function to formulate the problem, or...
Ever since the existence of negative refraction by metamaterial prisms was demonstrated by Pendry, Smith and others about a decade ago, the subject has received a tremendous amount of attention from many researchers around the world. A special class of MTMs, namely double negative or DNG type of artificially synthesized materials, has been used not only to design superlenses, but to also enhance the...
In this paper we describe an alternate technique that employs a hybrid formulation based upon a combination of the Dipole Moment (DM) approach with either the FEM or FDTD methods.
In this paper, we introduce a new general-purpose Computational Electromagnetics (CEM) algorithm, called RUFD (Recursive Algorithm Frequency Domain), for solving electromagnetic radiation and scattering problems in the frequency domain. The method shares many attributes with the Finite Difference Time Domain (FDTD), though it generates the solution of Maxwell's equations in the frequency rather than...
There exists a great need to develop numerical techniques for efficient solution of multiscale electromagnetic problems, regardless of the computational electromagnetics (CEM) method currently being used to tackle them, be it FEM, FDTD or MoM. Dealing with multiscale objects, which have features that are both small and large compared to the wavelength, is highly challenging and often forces us to...
In this work, the authors proposed a new method for the above field calculation, which utilizes the analytical expression for the near fields radiated by an electrically small dipole. The proposed method is found to be well suited for mitigating the problem of singularities encountered in the process of field computation while constructing the MoM matrix.
While the formulation of integral equations via the use of Green's functions is a well-established technique, it has been recognized that this formulation suffers from certain deficiencies. Some of these include low-frequency breakdown; need for special treatment of singularities of the ii-field representation in terms of the Green's function; lack of a universal formulation for handling perfect electric...
The paper presents a new dipole-moment-based approach for formulating MoM-type problems. The method is universal in nature and it applies equally well to PEC and dielectric objects. The dipole moment (DM) formulation neither suffers from the singularity problem associated with the Green's functions, nor does it experience any difficulties at low frequencies, as do the conventional MoM formulations.
The paper introduces a novel method for modeling powerline channels. The methodology is based on the use of three conductor transmission line. The mutual component of the three conductor line is varied to embrace the effects of multipath and impedance mismatches, without having any prior knowledge about them. In this way, the measured frequency response of the channel is finally reached. The method...
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