scholarly journals Modelling of Electromagnetic Scattering by a Hypersonic Cone-Like Body in Near Space

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Ji-Wei Qian ◽  
Hai-Li Zhang ◽  
Ming-Yao Xia
Keyword(s):  
Cross Sections ◽  
Electromagnetic Scattering ◽  
Numerical Procedure ◽  
Integral Equation Method ◽  
Dielectric Constants ◽  
The Body ◽  
Plasma Sheath ◽  
Surface Integral ◽  
Near Space ◽  
Radar Cross Sections

A numerical procedure for analysis of electromagnetic scattering by a hypersonic cone-like body flying in the near space is presented. First, the fluid dynamics equation is numerically solved to obtain the electron density, colliding frequency, and the air temperature around the body. They are used to calculate the complex relative dielectric constants of the plasma sheath. Then the volume-surface integral equation method is adopted to analyze the scattering properties of the body plus the plasma sheath. The Backscattering Radar Cross-Sections (BRCS) for the body flying at different speeds, attack angles, and elevations are examined. Numerical results show that the BRCS at a frequency higher than 300 MHz is only slightly affected if the speed is smaller than 7 Mach. The BRCS at 1 GHz would be significantly reduced if the speed is greater than 7 Mach and is continuously increased, which can be attributed to the absorption by the lossy plasma sheath. Typically, the BRCS is influenced by 5~10 dBm for a change of attack angle within 0~15 degrees, or for a change of elevation within 30~70 km above the ground.

scholarly journals The Investigation of EM Scattering from the Time-Varying Overturning Wave Crest Model by the IEM

2016 ◽  
Vol 2016 ◽  
pp. 1-8
Author(s):  
Xiao Meng ◽  
Li-xin Guo ◽  
Tian-qi Fan
Keyword(s):  
Cross Sections ◽  
3D Model ◽  
Three Dimensional ◽  
Integral Equation Method ◽  
Wave Crest ◽  
Time Varying ◽  
Spike Generation ◽  
Horizontal Polarization ◽  
Em Scattering ◽  
Radar Cross Sections

Investigation of the electromagnetic (EM) scattering of time-varying overturning wave crests is a worthwhile endeavor. Overturning wave crest is one of the reasons of sea spike generation, which increases the probability of false radar alarms and reduces the performance of multitarget detection in the environment. A three-dimensional (3D) time-varying overturning wave crest model is presented in this paper; this 3D model is an improvement of the traditional two-dimensional (2D) time-varying overturning wave crest model. The integral equation method (IEM) was employed to investigate backward scattering radar cross sections (RCS) at various incident angles of the 3D overturning wave crest model. The super phenomenon, where the intensity of horizontal polarization scattering is greater than that of vertical polarization scattering, is an important feature of sea spikes. Simulation results demonstrate that super phenomena may occur in some time samples as variations in the overturning wave crest.

Frame-transformation approximation for low-energy e−–1Σ+systems using the non-iterative integral equation method

1977 ◽  
Vol 55 (5) ◽  
pp. 442-451 ◽  
Author(s):  
Charles A. Weatherford ◽  
Ronald J. W. Henry
Keyword(s):  
Integral Equation ◽  
Cross Sections ◽  
Vibrational Excitation ◽  
Integral Equation Method ◽  
Laboratory Frame ◽  
The Body ◽  
Low Energy ◽  
Body Frame ◽  
Close Coupling ◽  
Frame Transformation

A discussion of the frame-transformation approximation appropriate for prediction of rotational and vibrational excitation cross sections for low-energy e−–1Σ+ systems is described. Explicit quantum number parameterizations of the time-independent Hamiltonian for both the body frame and the laboratory frame are given. A dynamical frame-transformation technique is described within the computational framework of the non-iterative, integral equation solution to the close-coupling scattering equations.

scholarly journals Electromagnetic Scattering Analysis of SHDB Objects Using Surface Integral Equation Method

Photonics ◽  
2020 ◽  
Vol 7 (4) ◽  
pp. 134
Author(s):  
Beibei Kong ◽  
Pasi Ylä-Oijala ◽  
Ari Sihvola
Keyword(s):  
Boundary Condition ◽  
Integral Equation ◽  
Electromagnetic Scattering ◽  
Three Dimensional ◽  
Circular Disk ◽  
Integral Equation Method ◽  
Surface Integral ◽  
Three Dimensional Objects ◽  
Surface Integral Equation ◽  
Scalar Equations

A surface integral equation (SIE) method is applied in order to analyze electromagnetic scattering by bounded arbitrarily shaped three-dimensional objects with the SHDB boundary condition. SHDB is a generalization of SH (Soft-and-Hard) and DB boundary conditions (at the DB boundary, the normal components of the D and B flux densities vanish). The SHDB boundary condition is a general linear boundary condition that contains two scalar equations that involve both the tangential and normal components of the electromagnetic fields. The multiplication of these scalar equations with two orthogonal vectors transforms them into a vector form that can be combined with the tangential field integral equations. The resulting equations are discretized and converted to a matrix equation with standard method of moments (MoM). As an example of use of the method, we investigate scattering by an SHDB circular disk and demonstrate that the SHDB boundary allows for an efficient way to control the polarization of the wave that is reflected from the surface. We also discuss perspectives into different levels of materialization and realization of SHDB boundaries.

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