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Mathematically strong and numerically efficient approach for simulation of waveguides and cylindrical resonators of arbitrary profile in the case of H-(TE-) polarized waves is suggested. The approach is based on new implementation of Analytical Regularization Method. Special attention paid to methods of the profiles infinitely smoothing, which gives a possibility to achieve a super-algebraic (faster...
A generalized geometrical optics type locally Floquet field expansion is presented for describing the field transmitted through a plane periodic wall when it is illuminated by a nearby antenna. It is developed from a rigorous plane wave spectral integral for the field associated with this problem, and the integral is evaluated asymptotically via a double stationary phase approach. This ray expansion...
Traditional high-value monostatic imaging systems employ frequency-diverse pulses to form images from small synthetic apertures. In contrast, RF tomography utilizes a network of spatially diverse sensors to trade geometric diversity for bandwidth, permitting images to be formed with narrowband waveforms. Such a system could use inexpensive sensors with minimal ADC requirements, provide multiple viewpoints...
Decoupling and matching feeding networks are considerably interested for small wireless terminals to enhance their abilities in the application for MIMO systems. This paper describes various kinds of decoupling and matching feeding networks and derives the formulas for determining the network elements explicitly. Numerical results are presented to ensure the formula for each decoupling and matching...
This paper presents a procedure of numerical code hybridization. It can be effectively used in a fast analysis and synthesis of the field patterns radiated from a phased array antenna. In particular, both low and high frequency methods are employed to simulate simultaneously the strong coupling within an antenna structure and its interactions with electrically large structure existed in its vicinity...
Boundary integral equations for bodies of revolution have a Green's function kernel that can be written as the azimuthal integral over the free-space Green's function. We show that existing approximation methods for computing this integral suffer from efficiency or stability problems. Improvement of one of these methods leads to controllable accuracy while retaining efficiency.
This paper presents a hybrid combination of the generalized ray expansion (GRE) method and high-frequency methods for analyzing the scattering and radiation problems incorporating electrically large and complex structures. A dense grid of ray tubes are launched from the phase centers of the subapertures making up the equivalent surface which encloses the target in the scattering problem, or the antenna...
The ability of microwave radar to detect and characterize obstacles below the sea surface is dependent on the extent to which perturbations of the surface geometry and dynamics resulting from either movement of the obstacle or disruption of waves and currents due to the presence of the obstacle can be discriminated from the natural state of the surface in the absence of such obstacles. In this paper...
A predicting methodology of scattering by a cluster of multi-objects/systems is proposed in this paper. In this predicting methodology, a representation of scattering by each object/system in the cluster is formulated with plane waves. Then an equation based on this plane wave representation is established for formulating interaction among objects/systems in the cluster. Finally, the equation is efficiently...
We tackle the scattering from a finite dielectric host medium containing a regular arrangement of (metallic or penetrable) inclusions by using the linear embedding via Green's operators method. After “dicing” the structure into “bricks”, we state an integral equation which we turn into a weak form via the Method of Moments (MoM) with subdomain basis functions. Then, to proceed i) we compress the off-diagonal...
Based on recently developed near-field iterative physical optics (NFIPO) and the Poynting vector method, near-field angular glint calculation formulations are derived and applied to perfect electric conducting (PEC) radar targets, which are of great importance for radar seeker applications. Numerical results are presented with new findings to demonstrate the usefulness of the proposed technique.
The primary objective of this paper is to study how the time-varying sea surface influences the electromagnetic (EM) scattering from ships. The mean and standard deviation of radar cross section (RCS) from targets on sea surface are discussed under different circumstances. The statistics of the phase gradient is also investigated using alpha-stable distribution. Simulation results show that the time-evolving...
The aim of this work is to quantify the observability of marine weather conditions using the bistatic Normalized Radar Cross Section (NRCS) from the sea surface. The mathematical model of the sea surface profiles is obtained from the Elfouhaily's spectrum and the NRCS are calculated using the Method of Moments (MoM). All of NRCS are recorded in some data sets depending on the weather conditions. Using...
A rigorous solution for the scattering problem of cylindrical lens reflector (CLR) due to an oblique incident plane wave is presented. The solution computed is based on the semi-analytic Method of Regularization (MoR), and hence, enjoys the properties of guaranteed accuracy and fast convergence. Numerical validations of the proposed algorithm, and study of the required truncation number Ntr are presented.
The response of aperture-backed cavities and other highly resonant scatterers can pose difficulties for general purpose computational codes, in both time- and frequency-domain. An accurate, numerically efficient frequency domain solution is developed for the scalar wave diffraction problem from an arbitrary shaped body of revolution, either closed or having an aperture. The Dirichlet boundary condition...
The authors conducted a sea clutter trial using a DSTO (Defence Science and Technology Organisation, Australia) built, vertically polarised, L-band, 16-channel receive array in May 2008 on the Kangaroo Island, South Australia. This paper studies some properties of the collected sea clutter, with an emphasis on observations of the interaction of electromagnetic waves with changes of the sea surface...
It has been recently shown that in the case of scattering by a perfect electric conductor, it is possible to have a convergent Method of Auxiliary Sources (MAS) field due to divergent MAS currents. These conclusions are extended in the present paper for the case of the implementation of MAS to dielectric scattering problems. The main differences are pointed out, which regard the existence of two critical...
Discoveries of new materials can lead to improved technologies - especially if relevant properties can be widely varied and precisely controlled. New materials may exhibit unexpected phenomena that motivate theoretical breakthroughs and quantitative models for optimizing devices. We discuss single crystal data for the R-type ferrites BaFe2±xRu4±xO11 and the Ruddleson-Popper phase Sr2IrO4, in which...
The finite element-boundary integral-multilevel fast multipole algorithm (FE-BI-MLFMA) has shown to be very general and powerful for 3D scattering. To efficiently model cavity targets, a concave FE-BI-MLFMA is presented in this paper, which can significantly reduce the dispersion error from the FEM and improve the efficiency of FE-BI-MLFMA especially for nonuniform cavities. To eliminate the problem...
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