scholarly journals An experimental realization of cylindrical cloaking using dogbone metamaterials

2017 ◽  
Vol 95 (10) ◽  
pp. 927-932 ◽  
Author(s):  
V.P. Sarin ◽  
M.P. Jayakrishnan ◽  
P.V. Vinesh ◽  
C.K. Aanandan ◽  
P. Mohanan ◽  
...  
Keyword(s):  
Plane Wave ◽  
Cross Section ◽  
Research Community ◽  
Experimental Realization ◽  
The Past ◽  
Scattered Power ◽  
Incident Plane ◽  
Effective Reduction ◽  
Target Metal ◽  
Wave Incidence

The quest for invisibility has inspired a deep ardour in the research community over the past decade. The invention of metamaterials has boosted the research on electromagnetic cloaking due to its unusual electromagnetic parameters under plane wave incidence. In this study, we propose a novel cloaking scheme, using dogbone metamaterials, for effectively routing the incident electromagnetic fields around a target metal cylinder under consideration. Notable reduction in the scattered power is observed from the target in comparison to an uncloaked target. Experiments and simulations validate an effective reduction in the scattering cross section of the target and effective guiding of the incident plane wave around the target.

scholarly journals Free space transmission lines in receiving antenna operation

2019 ◽  
Author(s):  
Reuven Ianconescu ◽  
Vladimir Vulfin
Keyword(s):  
Plane Wave ◽  
Cross Section ◽  
Incident Wave ◽  
Transmission Lines ◽  
Incident Plane Wave ◽  
Software Simulation ◽  
Incident Plane ◽  
Receiving Antenna ◽  
Scattering Matrices ◽  
Simulation Results

This work derives exact expressions for the voltage and current induced into a two conductors non isolated transmission lines by an incident plane wave. The methodology is to use the transmission line radiating properties to derive scattering matrices and make use of reciprocity to derive the response to the incident wave. The analysis is in the frequency domain and it considers transmission lines of any small electric cross section, incident by a plane wave from any incident direction and any polarisation. The analytic results are validated by successful comparison with ANSYS commercial software simulation results, and compatible with other published results.

scholarly journals Acoustic integrated extinction

2015 ◽  
Vol 471 (2177) ◽  
pp. 20150008 ◽  
Author(s):  
Andrew N. Norris
Keyword(s):  
Plane Wave ◽  
Cross Section ◽  
Acoustic Scattering ◽  
Forward Direction ◽  
Time Dependent ◽  
Incident Plane Wave ◽  
Scattering Function ◽  
Long Wavelength ◽  
Incident Plane ◽  
Finite Integral

The integrated extinction (IE) is defined as the integral of the scattering cross section as a function of wavelength. Sohl et al. (2007 J. Acoust. Soc. Am. 122 , 3206–3210. ( doi:10.1121/1.2801546 )) derived an IE expression for acoustic scattering that is causal, i.e. the scattered wavefront in the forward direction arrives later than the incident plane wave in the background medium. The IE formula was based on electromagnetic results, for which scattering is causal by default. Here, we derive a formula for the acoustic IE that is valid for causal and non-causal scattering. The general result is expressed as an integral of the time-dependent forward scattering function. The IE reduces to a finite integral for scatterers with zero long-wavelength monopole and dipole amplitudes. Implications for acoustic cloaking are discussed and a new metric is proposed for broadband acoustic transparency.

scholarly journals Suppression of Specular Reflections by Metasurface with Engineered Nonuniform Distribution of Reflection Phase

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Xin Mi Yang ◽  
Ge Lan Jiang ◽  
Xue Guan Liu ◽  
Cheng Xiang Weng
Keyword(s):  
Theoretical Model ◽  
Plane Wave ◽  
Cross Section ◽  
Nonuniform Distribution ◽  
Design Rule ◽  
New Approach ◽  
Reflection Phase ◽  
Specular Reflections ◽  
Wave Incidence ◽  
Plane Wave Incidence

We make preliminary investigations on a new approach to reducing radar cross section (RCS) of conducting objects. This approach employs novel planar metasurfaces characterizing nonuniform distribution of reflection phase. The operation principle of this approach and the design rule of the associated metasurfaces are explained using a simplified theoretical model. We then present a design example of such metasurfaces, in which three-layer stacked square patches with variable sizes are utilized as the reflecting elements. The proposed RCS-reduction approach is verified by both numerical simulations and measurements on the example, under the assumption of normal plane wave incidence. It is observed that, in a fairly wide frequency band (from 3.6 to 5.5 GHz), the presented example is capable of suppressing the specular reflections of conducting plates significantly (by more than 7 dB) for two orthogonal incident polarizations.

THE RADAR CROSS SECTION OF A SEMI-INFINITE BODY

1960 ◽  
Vol 38 (1) ◽  
pp. 48-56 ◽  
Author(s):  
H. Brysk
Keyword(s):  
Plane Wave ◽  
Cross Section ◽  
Ad Hoc ◽  
Simultaneous Occurrence ◽  
Body Of Revolution ◽  
Infinite Body ◽  
Incident Plane ◽  
The Cross ◽  
The Difference ◽  
Definition Of

The concept of cross section as applied to a semi-infinite scattering body seems to require some clarification. The need for careful formulation of the problem arises because of the simultaneous occurrence of two characteristic lengths tending to infinity: the range from the radar to the target, and the size of the target. The infinite range assumption in the definition of the cross section allows the incident wave to be approximated as a plane wave in the case of a finite scatterer. For a semi-infinite body, it is customary to retain the plane-wave incidence, and introduce ad hoc arguments to dispose of the awkwardness due to the infinite extent of the scatterer. A return to the basic definition of a cross section, and examination of its motivation, lead here to an unequivocal formulation for the cross section of a semi-infinite body. Its consequences are pursued in the physical optics approximation. In particular, the nose-on backscattering from a body of revolution is exhibited, and results are computed for the paraboloid and the cone (which turn out to agree with the traditional ones). The broadside backscattering from a cylinder is also calculated, and the difference in this case between mono-static backscattering and the return in the backward direction from an incident plane wave is discussed.

scholarly journals Elusive Pure Anapole Excitation in Homogenous Spherical Nanoparticles with Radial Anisotropy

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Wei Liu ◽  
Bing Lei ◽  
Jianhua Shi ◽  
Haojun Hu ◽  
Andrey E. Miroshnichenko
Keyword(s):  
Cross Section ◽  
Plane Waves ◽  
Far Field ◽  
Spherical Nanoparticles ◽  
Magnetic Dipoles ◽  
Anisotropic Dielectric ◽  
Scattered Power ◽  
Incident Plane ◽  
Total Scattering Cross Section ◽  
Radial Anisotropy

For homogenous isotropic dielectric nanospheres with incident plane waves, Cartesian electric and toroidal dipoles can be tunned to cancel each other in terms of far-field scattering, leading to the effective anopole excitation. At the same time however, other multipoles such as magnetic dipoles with comparable scattered power are simultanesouly excited, mixing with the anopole and leading to a nonnegligible total scattering cross-section. Here, we show that, for homogenous dielectric nanospheres, radial anisotropy can be employed to significantly suppress the other multipole excitation, which at the same time does not compromise the property of complete scattering cancallation between Cartesian electric and toroidal dipoles. This enables an elusivepure anopoleexcitation within radially anisotropic dielectric nanospheres, which may shed new light on many scattering related fundamental researches and applications.

Variation effect of plane-wave incidence on multiconductor transmission lines

2015 ◽  
Vol 8 (6) ◽  
pp. 891-898 ◽  
Author(s):  
Youssef Mejdoub ◽  
Hicham Rouijaa ◽  
Abdelilah Ghammaz
Keyword(s):  
Plane Wave ◽  
Transmission Lines ◽  
Method Of Characteristics ◽  
Incident Plane Wave ◽  
Incident Plane ◽  
Frequency Domains ◽  
Coupling Circuit ◽  
Multiconductor Transmission Line ◽  
Simulation Results ◽  
Wave Incidence

This paper addresses the study of the variation effects of incident plane wave on a multiconductor transmission line (MTL), using a coupling circuit model of MTL line with plane wave based on the method of characteristics (Branin method). This model is valid in the time and frequency domains. It has also an advantage of not presupposing the conditions of the charges applied to its ends, which allows it to be easily inserted in circuit simulators, such as SPICE, SABER, and ESACAP. We confirm the validity of this model by comparing our simulation results under ESACAP with other results, and we discuss the variation effects of the incident plane wave on an MTL line.

scholarly journals Symmetry Reduction in FEM Optics Modeling of Single and Periodic Nanostructures

Symmetry ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 752
Author(s):  
Henrik Mäntynen ◽  
Harri Lipsanen ◽  
Nicklas Anttu
Keyword(s):  
Plane Wave ◽  
Nanowire Array ◽  
Symmetry Reduction ◽  
Incident Plane Wave ◽  
Computationally Efficient ◽  
Incident Plane ◽  
Invaluable Tool ◽  
Numerical Performance ◽  
Diffraction Effects ◽  
Wave Incidence

Numerical optics modeling is an invaluable tool in the design of nanostructures for nanophotonics applications where diffraction effects often lead to complex dependency between the nanostructure geometry and its optical properties and response. In order to analyze, design, and optimize such nanostructures, computationally efficient numerical optics modeling methods are required. One way to improve the numerical performance is to exploit symmetries found in many optics problems. By identifying equivalencies and restrictions arising from symmetry, it can be possible to simplify the problem at hand, which is the essence of symmetry reduction. However, applying symmetry reduction in optics modeling problems is not trivial. To the best of our knowledge, symmetry reduction has so-far been applied in finite element method (FEM) optics models only in those specific cases where an incident plane wave shares symmetries with the nanostructure geometry. In this work, we show how to extend the symmetry reduction of FEM optics models to the case of nonsymmetric plane-wave incidence, demonstrate such reduction with numerical examples of incident plane wave absorption in a single nanowire and a periodic nanowire array, and discuss the achieved gains in computational efficiency.

Evaluating Qualitative Research

2017 ◽  
Author(s):  
Jeasik Cho
Keyword(s):  
Qualitative Research ◽  
Large Scale ◽  
Academic Research ◽  
Research Community ◽  
Assessment Tools ◽  
Journal Articles ◽  
Journal Editors ◽  
The Past ◽  
Grant Proposals

This book provides the qualitative research community with some insight on how to evaluate the quality of qualitative research. This topic has gained little attention during the past few decades. We, qualitative researchers, read journal articles, serve on masters’ and doctoral committees, and also make decisions on whether conference proposals, manuscripts, or large-scale grant proposals should be accepted or rejected. It is assumed that various perspectives or criteria, depending on various paradigms, theories, or fields of discipline, have been used in assessing the quality of qualitative research. Nonetheless, until now, no textbook has been specifically devoted to exploring theories, practices, and reflections associated with the evaluation of qualitative research. This book constructs a typology of evaluating qualitative research, examines actual information from websites and qualitative journal editors, and reflects on some challenges that are currently encountered by the qualitative research community. Many different kinds of journals’ review guidelines and available assessment tools are collected and analyzed. Consequently, core criteria that stand out among these evaluation tools are presented. Readers are invited to join the author to confidently proclaim: “Fortunately, there are commonly agreed, bold standards for evaluating the goodness of qualitative research in the academic research community. These standards are a part of what is generally called ‘scientific research.’ ”

scholarly journals Core-Shell Nano-Antenna Configurations for Array Formation with More Stability Having Conventional and Non-Conventional Directivity and Propagation Behavior

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 99
Author(s):  
Qaisar Hayat ◽  
Junping Geng ◽  
Xianling Liang ◽  
Ronghong Jin ◽  
Sami Ur Rehman ◽  
...  
Keyword(s):  
Plane Wave ◽  
Propagation Direction ◽  
Core Shell ◽  
Incident Plane Wave ◽  
Polarization Direction ◽  
Shell Nanoparticles ◽  
Incident Plane ◽  
Core Shell Nanoparticles ◽  
Coated Nanoparticle ◽  
2D Array

The enhancement of optical characteristics at optical frequencies deviates with the choice of the arrangement of core-shell nanoparticles and their environment. Likewise, the arrangements of core-shell nanoparticles in the air over a substrate or in liquid solution makes them unstable in the atmosphere. This article suggests designing a configuration of an active spherical coated nanoparticle antenna and its extended array in the presence of a passive dielectric, which is proposed to be extendable to construct larger arrays. The issue of instability in the core-shell nanoantenna array models is solved here by inserting the passive dielectric. In addition to this, the inclusion of a dielectric in the array model reports a different directivity behaviour than the conventional array models. We found at first that the combination model of the active coated nanoparticle and passive sphere at the resonant frequency can excite a stronger field with a rotated polarization direction and a propagation direction different from the incident plane-wave. Furthermore, the extended 2D array also rotates the polarization direction and propagation direction for the vertical incident plane-wave. The radiation beam operates strong multipoles in the 2D array plane at resonant frequency (behaving non-conventionally). Nevertheless, it forms a clear main beam in the incident direction when it deviates from the resonance frequency (behaving conventionally). The proposed array model may have possible applications in nano-amplifiers, nano-sensors and other integrated optics.

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