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Summary The theory of diffraction of electromagnetic waves by an ultrasonic wave in a crystal is discussed above. Expressions are obtained for the diffraction field in the near and the far zones. In the near zone the system is shown to be describable by the scattering matrix S of a 2(N+1)-pole, thus enabling the matrix method of network theory to be used for in vestigating different kinds of cascade connection of such systems. The expressions obtained contain the classical formulas of scalar diffraction in an isotropic layer as particular cases.Izvestiya VUZ. Radiofizika, Vol. 9, No. 1, pp. 16–32, 1966  相似文献   

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We have constructed a physicomathematical model of scattering of electromagnetic waves by a homogeneous object immersed in a material halfspace, which allows for anisotropy of electromagnetic properties of the scatterer and surrounding medium. This model is motivated by the need for remote sensing, nondestructive testing, and microwave devices and is based on the numerical solution of a system of integral equations for the electric field components inside an inclusion using the method of moments. We present numerical examples that illustrate wave scattering by an inhomogeneity in sea ice and polymer composite. State University, Khar’kov, Ukraine. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 40, No. 10, pp. 1249–1259, October, 1997.  相似文献   

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Lin CL  Wu JJ 《Optics letters》1998,23(1):22-24
We examine the value n(i)/n(eff)(theta(t)) , the ratio of the indices of refraction for waves transmitted from an isotropic medium to an anisotropic medium. It is found that total reflection can occur in the case of propagation from a rarer medium to a denser medium.  相似文献   

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A modification of Ambarzumian's method is used to develop the integro-differential equations for the source function, flux, and intensity at the boundary of a two-dimensional, semi-infinite cylindrical medium which scatters linearly. The incident radiation is collimated, normal to the top surface of the medium, and is dependent only on the radial coordinate. The radial variation is assumed to be a Bessel function or a Gaussian distribution. The Gaussian boundary condition is used to simulate a laser beam. Numerical results are presented in graphical and tabular forms for both boundary conditions. Results for forward and backward scattering phase functions are compared with those for isotropic scattering. A method is presented for extending these results to the problem of a strongly anisotropic phase function which is made up of a spike in the forward direction superimposed on a linear phase function.  相似文献   

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Integro-differential equations are developed for the source function, flux and intensity at the boundaries of a two-dimensional finite-thick medium which scatters in a linear fashion. The incident radiation is collimated, normal to the upper surface of the medium and dependent only on the radial coordinate. Two radial distributions are investigated: (1) a Bessel function and (2) a Gaussian laser beam. The solution for the Gaussian beam is constructed from the Bessel solution. Numerical results are presented in graphical and tabular forms for both boundary conditions. Comparisons are made between forward and isotropic scattering and between the finite and semi-infinite cases.  相似文献   

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The problem of propagation of electromagnetic waves in an inhomogeneous uniaxial anisotropic medium is discussed. Analytic solutions of Maxwell's equations are found for two particular cases of a plane-layered dielectric. The effect of different parameters of an inhomogeneous distribution of refractive indices on the propagation characteristics of wave beams is analyzed. The corrections of the first approximation of perturbation theory to the propagation constants of natural waves are obtained for a plane-layered focusing medium of general type. This has permitted solving the problem of a distribution of the refractive index which provides for optimal focusing.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 21, No. 12, pp. 1812–1821, December, 1978.In conclusion, the author expresses his gratitude to I. V. Ivanov and N. A. Morozov for their attention to this paper.  相似文献   

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杨利霞  葛德彪 《物理学报》2006,55(4):1751-1758
根据矩阵Padé逼近理论,把磁化色散介质的相对磁导率张量表示成以jω为自变量的矩阵函数形式,用/t代替jω后过渡到时域,再引入离散时域移位算子代替时间微分算子.进而导出磁化色散介质中的磁感应强度B和磁场强度H在离散时域的色散关系,并将其具体应用于旋磁介质,得到了这种磁化色散介质的Padé时域有限差分方法的递推表达式.作为验证,用这种方法计算了磁化铁氧体球的后向雷达散射截面,所得结果与文献结果一致.理论推导及算例表明,该方法是正确和有效的. 关键词: 各向异性介质 色散介质 矩阵Padé逼近 时域有限差分方法  相似文献   

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Exact results are presented for the source function, radiative flux, and intensity at the boundary of a two-dimensional, isotropically scattering, semi-infinite medium subjected to collimated or diffuse radiation. The spatial distributions of incident radiation considered are (1) cosine-varying, (2) semi-infinite step, (3) step at the origin and (4) finite strip. Two-dimensional effects are most pronounced at large albedos.  相似文献   

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The coefficient of extinction of electromagnetic waves of the microwave range due to their scattering from clusters suspended in an amorphous medium and responsible for turbidity is calculated. Turbidity resembles the case when butter clusters transform water into milk. In the case under investigation, the clusters are conductors (metallic or semiconducting). The extinction coefficient is connected in a familiar way with the cross section of light scattering from an individual cluster. A new formula is derived for the light scattering cross section in the case when damping of oscillations of an electron is due only to spontaneous emission of light quanta. In this case, the resonant scattering cross section for light can be very large. It is shown that this can be observed only in a whisker nanocluster. In addition, the phonon energy on a whisker segment must be higher than the photon energy, which is close to the spacing between the electron energy levels in the cluster.  相似文献   

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Information storage technology based on anisotropic ferromagnets with sufficiently high magneto-optical effects has received much attention in recent years.Magneto-optical recording combines the merits of magnetic and optical techniques.We investigate the magneto-optical effects on a biquadratic ferromagnet and show that the dynamics of the system are governed by a perturbed nonlinear Schro¨dinger equation.The evolutions of amplitude and velocity of the soliton are found to be time independent,thereby admitting the lossless propagation of the electromagnetic soliton in the medium,which may have potential applications in soliton based optical communication systems.We also exploit the role of perturbation,which has a significant impact on the propagation of an electromagnetic soliton.  相似文献   

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The propagation of s- and p-polarised electromagnetic plane waves in a N-layer system of anisotropic films on isotropic and homogeneous absorbing substrate is investigated in the long-wavelength limit. The analytical expressions are obtained for the reflection (transmission) coefficients and ellipsometric angles of an anisotropic multilayer system. All analytical results are correlated with the numerical solution of the reflection problem on the basis of rigorous electromagnetic theory for anisotropic layered systems. The possibilities of using obtained approximate formulae for resolving the inverse problem for ultrathin anisotropic dielectric films upon absorbing substrates are discussed.  相似文献   

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Beginning with the integral equation for the source function, the solutions for the source function, flux and intensity at the boundary of a two-dimensional, isotropically scattering cylindrical medium are found. The incident radiation is collimated and normal to the surface of the medium and depends only on the radial coordinate. For a Bessel function boundary condition, separation of variables is used to reduce the source function integral equation to a one-dimensional equation. The resulting integral equation is shown to be the same as that for the two-dimensional planar case. Solutions for other boundary conditions are then shown to be superpositions of the Bessel function solution. Numerical results are presented for a Gaussian distribution of incident radiation which closely models a laser beam. These multiple scattering results are compared to the single scattering approximation. Also, the solution for a strongly anisotropic phase function which is made up of a spike in the forward direction superimposed on an otherwise isotropic phase function is expressed in terms of the isotropic results.  相似文献   

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