Download or read book Analysis of the Em Scattering from Arbitrary Open Ended Waveguide Cavities Using Axial Gaussian Beam Tracking written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-06 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: The electromagnetic (EM) scattering from a planar termination located inside relatively arbitrarily shaped open-ended waveguide cavities with smoothly curved interior walls is analyzed using a Gaussian Beam (GB) expansion of the incident plane wave fields in the open end. The cavities under consideration may contain perfectly-conducting interior walls with or without a thin layer of material coating, or the walls may be characterized by an impedance boundary condition. In the present approach, the GB's are tracked only to the termination of the waveguide cavity via beam reflections from interior waveguide cavity walls. The Gaussian beams are tracked approximately only along their beam axes; this approximation which remains valid for relatively well focussed beams assumes that an incident GB gives rise to a reflected GB with parameters related to the incident beam and the radius of curvature of the wall. It is found that this approximation breaks down for GB's which come close to grazing a convex surface and when the width of the incident beam is comparable to the radius of curvature of the surface. The expansion of the fields at the open end depend on the incidence angle only through the expansion coefficients, so the GB's need to be tracked through the waveguide cavity only once for a wide range of incidence angles. At the termination, the sum of all the GB's are integrated using a result developed from a generalized reciprocity principle, to give the fields scattered from the interior of the cavity. The rim edge at the open end of the cavity is assumed to be sharp and the external scattering from the rim is added separately using Geometrical Theory of Diffraction. The results based on the present approach are compared with solutions based on the hybrid asymptotic modal method. The agreement is found to be very good for cavities made up of planar surfaces, and also for cavities with curved surfaces which are not too long with respect to their width. Burkholder, R. ...
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1989 with total page 988 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1989 with total page 1148 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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Download or read book International Symposium Digest Antennas and Propagation written by IEEE Antennas and Propagation Society. International Symposium and published by . This book was released on 1993 with total page 904 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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Download or read book International Aerospace Abstracts written by and published by . This book was released on 1984 with total page 1198 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Non diffracting Waves written by Hugo E. Hernández-Figueroa and published by John Wiley & Sons. This book was released on 2013-09-25 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt: This continuation and extension of the successful book "Localized Waves" by the same editors brings together leading researchers in non-diffractive waves to cover the most important results in their field and as such is the first to present the current state. The well-balanced presentation of theory and experiments guides readers through the background of different types of non-diffractive waves, their generation, propagation, and possible applications. The authors include a historical account of the development of the field, and cover different types of non-diffractive waves, including Airy waves and realistic, finite-energy solutions suitable for experimental realization. Apart from basic research, the concepts explained here have promising applications in a wide range of technologies, from wireless communication to acoustics and bio-medical imaging.
Download or read book High Frequency Asymptotic Methods for Analyzing the Em Scattering by Open Ended Waveguide Cavities written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-25 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: Four high-frequency methods are described for analyzing the electromagnetic (EM) scattering by electrically large open-ended cavities. They are: (1) a hybrid combination of waveguide modal analysis and high-frequency asymptotics, (2) geometrical optics (GO) ray shooting, (3) Gaussian beam (GB) shooting, and (4) the generalized ray expansion (GRE) method. The hybrid modal method gives very accurate results but is limited to cavities which are made up of sections of uniform waveguides for which the modal fields are known. The GO ray shooting method can be applied to much more arbitrary cavity geometries and can handle absorber treated interior walls, but it generally only predicts the major trends of the RCS pattern and not the details. Also, a very large number of rays need to be tracked for each new incidence angle. Like the GO ray shooting method, the GB shooting method can handle more arbitrary cavities, but it is much more efficient and generally more accurate than the GO method because it includes the fields diffracted by the rim at the open end which enter the cavity. However, due to beam divergence effects the GB method is limited to cavities which are not very long compared to their width. The GRE method overcomes the length-to-width limitation of the GB method by replacing the GB's with GO ray tubes which are launched in the same manner as the GB's to include the interior rim diffracted field. This method gives good accuracy and is generally more efficient than the GO method, but a large number of ray tubes needs to be tracked. Burkholder, R. J. and Pathak, P. H. Unspecified Center NASA-CR-186244, NAS 1.26:186244, ESL-TR-719630-3 NAG3-476...
Download or read book Modern Antenna Design written by Thomas A. Milligan and published by John Wiley & Sons. This book was released on 2005-07-11 with total page 646 pages. Available in PDF, EPUB and Kindle. Book excerpt: A practical book written for engineers who design and use antennas The author has many years of hands on experience designing antennas that were used in such applications as the Venus and Mars missions of NASA The book covers all important topics of modern antenna design for communications Numerical methods will be included but only as much as are needed for practical applications
Download or read book Optical Tweezers written by Philip H. Jones and published by Cambridge University Press. This book was released on 2015-12-03 with total page 565 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive guide to the theory, practice and applications of optical tweezers, combining state-of-the-art research with a strong pedagogic approach.
