MEASUREMENTS ON ELECTROMAGNETIC SCATTERED FIELDS OF SOME RF AND MICROWAVE EQUIPMENTS

2017 ◽  
Vol 16 (10) ◽  
pp. 2371-2380
Author(s):  
Sorin-Bogdan Balmus ◽  
Dumitru D. Sandu ◽  
Paul Gasner ◽  
Sorin Dobrea
Keyword(s):  
Scattered Fields

scholarly journals Ultrasonic Scattered Field Distribution of One and Two Cylindrical Solids with Phased Array Technique

2019 ◽  
Vol 32 (1) ◽  
Author(s):  
Xiaozhou Liu ◽  
Jian Ma ◽  
Haibin Wang ◽  
Sha Gao ◽  
Yifeng Li ◽  
...  
Keyword(s):  
Plane Wave ◽  
Field Distribution ◽  
Scattered Field ◽  
Phased Array ◽  
Simulation Analysis ◽  
Plane Waves ◽  
Theoretical Solution ◽  
Steel Matrix ◽  
Field Distributions ◽  
Scattered Fields

AbstractThe scattered fields of plane waves in a solid from a cylinder or sphere are critical in determining its acoustic characteristics as well as in engineering applications. This paper investigates the scattered field distributions of different incident waves created by elastic cylinders embedded in an elastic isotropic medium. Scattered waves, including longitudinal and transverse waves both inside and outside the cylinder, are described with specific modalities under an incident plane wave. A model with a scatterer embedded in a structural steel matrix and filled with aluminum is developed for comparison with the theoretical solution. The frequency of the plane wave ranged from 235 kHz to 2348 kHz, which corresponds to scaling factors from 0.5 to 5. Scattered field distributions in matrix materials blocked by an elastic cylindrical solid have been obtained by simulation or calculated using existing parameters. The simulation results are in good agreement with the theoretical solution, which supports the correctness of the simulation analysis. Furthermore, ultrasonic phased arrays are used to study scattered fields by changing the characteristics of the incident wave. On this foundation, a partial preliminary study of the scattered field distribution of double cylinders in a solid has been carried out, and the scattered field distribution at a given distance has been found to exhibit particular behaviors at different moments. Further studies on directivities and scattered fields are expected to improve the quantification of scattered images in isotropic solid materials by the phased array technique.

Analytic solutions of the scattering by two multilayered dielectric spheres

1992 ◽  
Vol 70 (9) ◽  
pp. 696-705 ◽  
Author(s):  
A-K. Hamid ◽  
I. R. Ciric ◽  
M. Hamid
Keyword(s):  
Boundary Conditions ◽  
Cross Sections ◽  
Plane Electromagnetic Wave ◽  
Expansion Method ◽  
Analytic Solutions ◽  
Addition Theorem ◽  
Modal Expansion ◽  
Modal Expansion Method ◽  
Dielectric Spheres ◽  
Scattered Fields

The problem of plane electromagnetic wave scattering by two concentrically layered dielectric spheres is investigated analytically using the modal expansion method. Two different solutions to this problem are obtained. In the first solution the boundary conditions are satisfied simultaneously at all spherical interfaces, while in the second solution an iterative approach is used and the boundary conditions are satisfied successively for each iteration. To impose the boundary conditions at the outer surface of the spheres, the translation addition theorem of the spherical vector wave functions is employed to express the scattered fields by one sphere in the coordiante system of the other sphere. Numerical results for the bistatic and back-scattering cross sections are presented graphically for various sphere sizes, layer thicknesses and permittivities, and angles of incidence.

scholarly journals Zeeman gyrotropic scatterers

2018 ◽  
Vol 8 ◽  
pp. 184798041880808 ◽  
Author(s):  
Constantinos Valagiannopoulos ◽  
S Ali Hassani Gangaraj ◽  
Francesco Monticone
Keyword(s):  
Zeeman Splitting ◽  
Core Shell ◽  
Anomalous Scattering ◽  
Important Class ◽  
Fano Resonances ◽  
The Past ◽  
Scattering Effects ◽  
Full Analysis ◽  
The Subject ◽  
Scattered Fields

Anomalous scattering effects (invisibility, superscattering, Fano resonances, etc) enabled by complex media and metamaterials have been the subject of intense efforts in the past couple of decades. In this article, we present a full analysis of the unusual and extreme scattering properties of an important class of complex scatterers, namely, gyrotropic cylindrical bodies, including both homogeneous and core–shell configurations. Our study unveils a number of interesting effects, including Zeeman splitting of plasmonic scattering resonances, tunable gyrotropy-induced rotation of dipolar radiation patterns as well as extreme Fano resonances and non-radiating eigenmodes (embedded eigenstates) of the gyrotropic scatterer. We believe that these theoretical findings may enable new opportunities to control and tailor scattered fields beyond what is achievable with isotropic reciprocal objects, being of large significance for different applications, from tunable directive nano-antennas to selective chiral sensors and scattering switches, as well as in the context of nonreciprocal and topological metamaterials.

scholarly journals Sound diffraction on an elastic spheroidal shell

2021 ◽  
Vol 3 (397) ◽  
pp. 97-114
Author(s):  
A. Kleschev ◽  
Keyword(s):  
Group Velocity ◽  
Planar Waveguide ◽  
Sound Propagation ◽  
Spectral Characteristics ◽  
Sound Field ◽  
Signal Propagation ◽  
Elastic Bottom ◽  
Harmonic Signals ◽  
Scattered Fields ◽  
Sound Diffraction

Object and purpose of research. This paper obtains solutions and performs estimations of characteristics of sound reflection and scattering by ideal and elastic bodies of various shapes (analytical and non-analytical) near media interface, or underwater sonic channel, or in a planar waveguide with a solid elastic bottom. Materials and methods. The harmonic signals are investigated with the method of normal waves based on the phase velocity of signal propagation, and impulse signals related to the energy transfer are studied using the method of real and imaginary sources and scatterers based on the group velocity of propagation. Main results. The scattered sound field is calculated for ideal spheroids (elongated and compressed) at fluid – ideal medium interface. The spectrum of a scattered impulse signal is calculated for a body placed in a sonic channel. First reflected impulses are found for an ideal spheroid in a planar waveguide with anisotropic bottom. Conclusion. In the studies of diffraction characteristics of bodies at media interfaces it was found that the main contribution to scattered field is given by interference of scattered fields rather than interaction of scatterers (real or imaginary). It is shown that at long distances the spectral characteristics of the channel itself have a prevalent role. When impulse sound signals in the planar waveguide are used, it is necessary to apply the method of real and imaginary sources and scatterers based on the group velocity of sound propagation.

On the degrees of freedom of scattered fields

1989 ◽  
Vol 37 (7) ◽  
pp. 918-926 ◽  
Author(s):  
O.M. Bucci ◽  
G. Franceschetti
Keyword(s):  
Degrees Of Freedom ◽  
Scattered Fields

Acoustic invisibility in turbulent fluids by optimised cloaking

2014 ◽  
Vol 749 ◽  
pp. 460-477 ◽  
Author(s):  
Xun Huang ◽  
Siyang Zhong ◽  
Xin Liu
Keyword(s):  
Theoretical Model ◽  
Computational Methods ◽  
Physical Mechanism ◽  
Far Field ◽  
Turbulent Wakes ◽  
Scattered Fields ◽  
Turbulent Fluids

AbstractAcoustic invisibility of a cloaking system in turbulent fluids is poorly understood. Here we show that evident scattering would appear in turbulent wakes due to the submergence of a classical cloaking device. The inherent physical mechanism is explained using our theoretical model, which eventually inspires us to develop an optimised cloaking approach. Both the near- and far-field scattered fields are examined using computational methods. The remarkably low scattering demonstrates the effectiveness of the proposed approach, in particular for acoustic cloaking in turbulent fluids.

Analysis for Scattering of Non-homogeneous Medium by Time Domain Volume Shooting and Bouncing Rays

2021 ◽  
Vol 36 (3) ◽  
pp. 245-251
Author(s):  
Jun Li ◽  
Huaguang Bao ◽  
Dazhi Ding
Keyword(s):  
Time Domain ◽  
Electromagnetic Scattering ◽  
Electromagnetic Waves ◽  
High Efficiency ◽  
Homogeneous Medium ◽  
Reflection And Transmission ◽  
Transmission Coefficients ◽  
Transient Electromagnetic ◽  
Frequency Domain Methods ◽  
Scattered Fields

In order to evaluate scattering from hypersonic vehicles covered with the plasma efficiently, time domain volume shooting and bouncing rays (TDVSBR) is first introduced in this paper. The new method is applied to solve the transient electromagnetic scattering from complex targets, which combines with non-homogeneous dielectric and perfect electric conducting (PEC) bodies. To simplify the problem, objects are discretized into tetrahedrons with different electromagnetic parameters. Then the reflection and transmission coefficients can be obtained by using theory of electromagnetic waves propagation in lossy medium. After that, we simulate the reflection and transmission of rays in different media. At last, the scattered fields or radiation are solved by the last exiting ray from the target. Compared with frequency-domain methods, time-domain methods can obtain the wideband RCS efficiently. Several numerical results are given to demonstrate the high efficiency and accuracy of this proposed scheme.

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