1,720,987 research outputs found
Uniform Asymptotic Evaluation of Surface Integrals With Polygonal Integration Domains in Terms of UTD Transition Functions
No full textThe field scattered by a scattering body or by an aperture in the free space (or in an unbounded homogenous medium) can be described in terms of a double integral. In this paper we show how a canonical integral on a polygonal domain, with a constant amplitude function and a quadratic phase variation, can be exactly expressed in terms of special functions, namely Fresnel integrals and generalized Fresnel integrals. This exact reduction represents a paradigm for deriving a new asymptotic evaluation for a more general integral. This new asymptotic uniform integral evaluation is expressed in the format of the uniform geometrical theory of diffraction which is convenient for numerical computations
A NEW UTD BASED RELATION BETWEEN MODIFIED PAULI-CLEMMOW AND VAN DER WAERDEN METHODS FOR ASYMPTOTIC EVALUATION OF WEDGE DIFFRACTION INTEGRALS
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An efficient DFT-UTD based array synthesis via the successive projection method for contoured beam applications
No full textA fast hybrid DFT-MoM for the analysis of large finite periodic antenna arrays in grounded layered media
No full textAn Efficient DFT-UTD Based Evaluation of the Field radiated by Electrically Large Phased Arrays
No full textA Fast Hybrid DFT-MoM for the Analysis of Large Finite Periodic Antenna Arrays on Grounded Substrates
No full textOn Two Alternative Uniformly Asymptotic Procedures for Analyzing the High-Frequency Diffraction of a Complex Source Beam by a Straight Wedge
Full text linkWhen spectral wave integrals, representing the radiation and diffraction of electromagnetic waves, are characterized by a first-order saddle point and poles in the integrand, they can usually be evaluated, in essentially closed form, at high frequencies by the leading terms of any of the two well-known alternative uniformly asymptotic procedures, namely, the Pauli-Clemmow method (PCM) and the Van der Waerden method (VWM), respectively. The PCM has the advantage that its leading terms directly yield a solution in the simple ray format of the uniform geometrical theory of diffraction (UTD). On the other hand, it is commonly noted that it is not the leading term of the PCM but that of the VWM which remains valid for the case of complex waves. Nevertheless, it is shown here that the PCM can surprisingly work even for some special complex wave cases, only if certain conditions are met. Indeed, it is demonstrated here that the PCM meets these conditions for the special case of the diffraction of a complex source beam (CSB) by a wedge. Also, the PCM directly yields a UTD like solution for this case. The latter result is significant as it provides a strong justification for obtaining a simple UTD type solution for the more general problem of the diffraction of a CSB incident from an arbitrary direction on a wedge with arbitrary curvature, directly via analytic continuation of the corresponding UTD result available for a curved wedge illuminated by a point source in real space. It is also shown that the VWM solution can be trivially cast in the UTD format, by expressing it as a sum of the PCM solution plus a UTD slopelike correction term; a similar result was obtained previously using a higher order term from a generalization of the PCM procedure given elsewhere
A review of some UTD developments - past and present
No full textA review of some early UTD developments following Keller's introduction of the GTD is described. That is followed bya description of more recent developments and future trends in UTD for solving problems of predicting the performance of antennas on complex metallic structures with thin material coating
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