Author

# Raj Mittra

Other affiliations: University of Kentucky, University of Colorado Boulder, California Institute of Technology ...read more

Bio: Raj Mittra is an academic researcher from University of Central Florida. The author has contributed to research in topics: Finite-difference time-domain method & Antenna (radio). The author has an hindex of 79, co-authored 1444 publications receiving 29317 citations. Previous affiliations of Raj Mittra include University of Kentucky & University of Colorado Boulder.

##### Papers published on a yearly basis

##### Papers

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01 Dec 1988TL;DR: In this article, a number of representative techniques for analyzing frequency-selective surfaces (FSSs), which comprise periodic arrays of patches or apertures in a conducting screen and find important applications as filters in microwaves and optics, are discussed.

Abstract: A number of representative techniques for analyzing frequency-selective surfaces (FSSs), which comprise periodic arrays of patches or apertures in a conducting screen and find important applications as filters in microwaves and optics, are discussed. The basic properties of the FSSs are reviewed and several different approaches to predicting their frequency-response characteristics are described. Some recent developments in the treatment of truncated, curved, and doubly periodic screens are mentioned and representative experimental results are included. >

1,060 citations

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TL;DR: A novel approach for an efficient solution of matrix equations arising in the method of moments (MoM) formulation of electromagnetic scattering problems is introduced, based on the characteristic basis functions (CBFs), which are used to substantially reduce the matrix size.

Abstract: In this paper, we introduce a novel approach for an efficient solution of matrix equations arising in the method of moments (MoM) formulation of electromagnetic scattering problems. This approach is based on the characteristic basis functions (CBFs), which are used to substantially reduce the matrix size because these bases are not bound by the conventional λ/20 domain discretization. As a result, it is possible to electrically solve large problems with much fewer unknowns than those needed when using conventional RWG basis functions. The accuracy and efficiency of the CBFs are demonstrated in a variety of scattering problems to illustrate the versatility of the approach. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 36: 95–100, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10685

580 citations

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Abstract: A procedure for synthesizing multilayered radar absorbing coatings is presented. Given a predefined set of N/sub m/ available materials with frequency-dependent permittivities in /sub i/(f) and permeabilities mu /sub i/(f) (i=1,. . ., N/sub m/), the technique determines simultaneously the optimal material choice for each layer and its thickness. This optimal choice results in a screen which maximally absorbs TM and TE incident plane waves for a prescribed range of frequencies (f/sub 1/,f/sub 2/,. . ., f/sub N/f) and incident angles ( theta /sub 1/, theta /sub 2/,. . ., theta /sub N theta /). The synthesis technique is based on a genetic algorithm. The technique automatically places an upper bound on the total thickness of the coating, as well as the number of layers contained in it, which greatly simplifies manufacturing. In addition, the thickness or surface mass of the coating can be minimized simultaneously with the reflection coefficient. The algorithm was successfully applied to the synthesis of wideband absorbing coatings in the frequency ranges of 0.2-2 GHz and 2-8 GHz. >

543 citations

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TL;DR: In this paper, the electric field integral equation (EFIE) is used with the moment method to develop a simple and efficient numerical procedure for treating problems of scattering by arbitrarily shaped objects.

Abstract: The electric field integral equation (EFIE) is used with the moment method to develop a simple and efficient numerical procedure for treating problems of scattering by arbitrarily shaped objects. For numerical purposes, the objects are modeled using planar triangular surfaces patches. Because the EFIE formulation is used, the procedure is applicable to both open and closed surfaces. Crucial to the numerical formulation is the development of a set of special subdomain-type basis functions which are defined on pairs of adjacent triangular patches and yield a current representation free of line or point charges at subdomain boundaries. The method is applied to the scattering problems of a plane wave illuminated flat square plate, bent square plate, circular disk, and sphere. Excellent correspondence between the surface current computed via the present method and that obtained via earlier approaches or exact formulations is demonstrated in each case.

4,835 citations

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TL;DR: An overview of beamforming from a signal-processing perspective is provided, with an emphasis on recent research.

Abstract: An overview of beamforming from a signal-processing perspective is provided, with an emphasis on recent research. Data-independent, statistically optimum, adaptive, and partially adaptive beamforming are discussed. Basic notation, terminology, and concepts are included. Several beamformer implementations are briefly described. >

4,122 citations

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TL;DR: In this article, the authors used the discrete-dipole approximation (DDA) for scattering calculations, including the relationship between the DDA and other methods, including complex-conjugate gradient algorithms and fast-Fourier transform methods.

Abstract: The discrete-dipole approximation (DDA) for scattering calculations, including the relationship between the DDA and other methods, is reviewed. Computational considerations, i.e., the use of complex-conjugate gradient algorithms and fast-Fourier-transform methods, are discussed. We test the accuracy of the DDA by using the DDA to compute scattering and absorption by isolated, homogeneous spheres as well as by targets consisting of two contiguous spheres. It is shown that, for dielectric materials (|m| ≲ 2), the DDA permits calculations of scattering and absorption that are accurate to within a few percent.

3,283 citations

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01 Nov 1981TL;DR: In this paper, a summary of many of the new techniques developed in the last two decades for spectrum analysis of discrete time series is presented, including classical periodogram, classical Blackman-Tukey, autoregressive (maximum entropy), moving average, autotegressive-moving average, maximum likelihood, Prony, and Pisarenko methods.

Abstract: A summary of many of the new techniques developed in the last two decades for spectrum analysis of discrete time series is presented in this tutorial. An examination of the underlying time series model assumed by each technique serves as the common basis for understanding the differences among the various spectrum analysis approaches. Techniques discussed include the classical periodogram, classical Blackman-Tukey, autoregressive (maximum entropy), moving average, autotegressive-moving average, maximum likelihood, Prony, and Pisarenko methods. A summary table in the text provides a concise overview for all methods, including key references and appropriate equations for computation of each spectral estimate.

2,941 citations