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The paper presents work done for determination of range, velocity and direction of motion of one or more UHF RFID-tagged objects present within a broadcast-and-receive range of an RFID tag reader using the Phase-Difference-of-Arrival concept. Different processing techniques with respective advantages and disadvantages are presented. Theoretical methods are developed, data collected in various environmental...
Summary form only given. Commercial EM simulation softwares are invaluable tools without which the engineers, who are engaged in designing antennas, microwave circuits, RF packages, and systems utilizing these devices, simply cannot survive. This is because the number of real-world problems that we can solve by using analytical techniques is very limited indeed. To be sure, the commercial software...
In this paper, we will present some recent developments of flat-lens designs for microwave imaging applications at the EMC Laboratory of Perm State. We will also describe a procedure for systematically synthesizing artificial dielectrics, e.g., MTMs, for flat lens designs that can achieve a sub-wavelength focal plane behavior. The design has the advantages of being wideband and low-loss, and it is...
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.
We present a scheme to realize an undetectable reflector antenna. Discrete coordinate transformation is employed to design an `invisible' carpet cloak which is functional to hide objects underneath. A parabolic reflector located under the designed carpet cloak is rendered undetectable to the external observers whilst still possessing its radiation characteristics. Furthermore, a novel kind of underground...
Two time-honored questions that the practitioners of Computational Electromagnetics (CEM) are frequently asked by their colleagues engaged in the design of electromagnetic systems are: (i) What is new in CEM; and (ii) What can you do to solve my problems. Their curiosity probably stems from the fact that CEM is being used more and more as a design tool for a wide variety of electromagnetic problems...
This paper describes a newly developed dipole moment (DM) approach, for modeling periodic structures. It is both memory- and time-efficient, and is applicable to arbitrarily shaped elements, whose material properties can also be arbitrary.
In recent years, ever-increasing proliferation of handheld terminals has served to enhance the level of concern for possible deleterious biological effects of electromagnetic waves absorbed by the human body. Generally speaking, when the cellular mobile radio system is functioning, and the transmitting terminal is located in close proximity of the human head-say less than 7 mm-a large fraction of...
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 paper we present an efficient technique for analyzing RF and microwave circuits printed on layered media. The method is based on combining a new Equivalent Medium Approach (EMA) — which obviates that need to construct layered medium Green's functions — with the Characteristic Basis Function Method (CBFM). A numerical example, which illustrates the accuracy and efficiency of the proposed approach...
In this paper, the authors describe a new technique for modeling periodic structures that is both memory and time efficient. The method presented is general and for the sake of illustration, frequency selective surface (FSS) elements comprising of wire tripoles was chosen.
In this paper we discuss some of the challenging issues arising in the process of designing broadband matching systems for small antennas that are inherently high-Q devices. One of the novel approaches to realizing broadband performance from a small antenna is to consider the possibility of loading it with metamaterials that have negative epsilon characteristics. It has been conjectured that it may...
In this paper, we introduce a novel method, which we call Finite Element / Dipole Moment Method (FEDM), with two alternative (iterative and self-consistent) implementations, for handling the multiscale problem mentioned above. In this method, the conventional FEM is modified through the use of dipole moments in such a way that the region around the thin/small object is extracted and the object is...
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 FDTD method provided we have access to adequate computational resources, the method can quickly become unattractive for a multiscale problem, in which the computational domain size is extremely large (on the order of tens of wavelengths) and several of the features within the model are much less than the wavelength (on the order of hundredths or thousandths of a wavelength). These scenarios frequently...
In this paper, we present a method to accurately and efficiently compute the radiation from a numerically-defined set of currents represented in terms of a modified version of the classical rooftop basis functions. The shape of the scatterer is completely arbitrary and may be defined by NURBS surfaces [4], Since a NURBS representation is used in most of the CAD design software, this formulation enables...
In this paper, we present the design of a two-layer microwave absorber with ultra-wideband performance, covering the range of 4.6 to 18 GHz. An analysis of the impedance transformation characteristics of the two-layer system is included to help understand how the low impedance of a PEC plane is mapped into the matched-condition by the two layers.
In this work we present a systematic approach for designing planar lenses using artificial dielectrics to realize the desired phase delays. The artificial dielectric is synthesized by using multilayer frequency selective surfaces (FSSs) with Jerusalem Cross (JC) elements, because they are found to be good candidates that provide stable response over a wide range of incident angles and for both polarizations.
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