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We describe an all-dielectric metasurface, based on elliptic dielectric resonators (EDRs), which is designed to work as a beam splitter at 16.98 GHz. The proposed metasurface refracts electromagnetic incident waves with orthogonal polarizations along two specific directions without reflection.
Given the well documented health effects of electromagnetic radiation on humans, the SAR reduction techniques are becoming increasingly relevant to the industry. However, satisfying the bandwidth, efficiency, size and cost requirements of a low SAR solution for the new mobile terminals remains elusive to-date. This paper presents a method for designing an SAR shield, based on combined use of graphene-type...
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 present a flat lens based on a zoned two-layer design, which provides us the freedom to simultaneously control the magnitude and phase of the transmitted wave passing through the lens. A transmission line approach is used to analyze the reflection and transmission coefficients of the proposed two-layer slab, and a two-step method is introduced to determine the distribution of the...
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...
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 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...
Because the EBGs and Metamaterial structures that exhibit interesting characteristics are almost always strictly periodic in nature and because there is an increasing interest in synthesizing new versions of these structures, we need access to both techniques-and computer codes developed on the basis of these techniques-to accomplish our own design goals. Some of the design objectives of Metamaterials...
Research activities in the area of Metamaterials (MTMs)-especially Negative Refractive Index (NRI) media-have been truly intense during the last ten years, and these activities are likely to continue on unabated during the next decade. In this presentation we will critically examine the potential use of metamaterials for a number of practical applications for which they appear to be promising.
Perhaps no single topic under the general umbrella of Metamaterials has elicited the recent attention of so many researchers as has the subject of “Cloaking”, which deals with the problem of making objects disappear - so to speak - because the cloaking material wrapped around the object bends the paths of the impinging light rays in a manner such that they skirt around the object; and, hence, the...
In this paper, we first discuss the parameter extraction problem associated with a well known DNG element, namely the wire and split ring resonator (SRR) combination. Next, we present the simulation results for the electric field distribution in another DNG structure, namely the mushroom, which is excited by a probe source. Both of these simulations are carried out by using the parallelized FDTD code...
In this talk we will begin by reviewing the fundamentals of Metamaterials by asking the question: "How do we categorize metamaterials and derive their effective medium properties?" We will then go on to address a related question that is very relevant from the point of view of a practicing engineer, namely: "How can they help us build better 'widgets', such as flat superlenses, highly-directive...
In this work, we have investigated the mechanism of performance enhancement of a dipole antenna located above a ground plane, and covered by a dielectric EBG superstrate. We show that the maximum enhancement in the received power can be up to 9.3 dB for the composite. We have gained considerable insight into the mechanism of directivity enhancement that should help us with future designs.
Typically, most of the studies on metamaterials ignore the interaction between split-ring resonators and cut-wires, and also between identical resonators of the two arrays. They view the electromagnetic response of metamaterials as though it is a simple summation of responses of the individual elements. The elements are assumed to be ldquonot seenrdquo by the waves, which are thought to propagate...
In this paper we determine the weights of the spatial harmonics in a periodic structure, with quasi-periodicity along the propagation direction, by detailed analysis of the fields inside the unit-cells. We use both the Pronypsilas method and Fourier transform to extract the spectrum of the fields inside the unit cells along the propagation direction and compare the results obtained by each method...
In this paper we study the antenna/woodpile electronic bandgap (EBG) composite by using the finite difference time domain (FDTD) Method. The near-field as well as far-field performance are examined at different frequencies with a view to realizing enhanced directivity. In addition, the structure is modeled and simulated under plane wave illumination and the scattered fields are computed to gain an...
Performance enhancement of small conformal antennas, e.g., microstrip patch antennas (MPA's) is often accomplished by adding a superstrate or a substrate, comprising of artificial dielectrics that are also referred to as metamaterials, especially when the effective parameters differ substantially from those of the constituent media. These embellishments to the MPA are designed to increase its effective...
The purpose of this review paper is to critically examine some the physics-based fundamental limitations. Using metamaterials and/or other exotic physical phenomena for performance. This, in turn, prompts us to critically examine the effective medium theories, and rigorously model the physical structures that show promise rather than their effective medium equivalents to see if indeed their actual...
In this review paper we take a critical look at the problem of performance enhancement of small antennas using metamaterials. We first review the definitions of metamaterials that have been used in the literature, and then introduce our own classification of metamaterials in the microwave regime - that are artificial dielectrics - by dividing them into two broad sub-categories. Representative examples...
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