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Cylindrical Waveguide (cylindrical + waveguide)

Distribution by Scientific Domains
Mathematics and Statistics75%

Selected Abstracts

A gap in the essential spectrum of a cylindrical waveguide with a periodic aperturbation of the surface

MATHEMATISCHE NACHRICHTEN, Issue 9 2010
Giuseppe Cardone
Abstract It is proved that small periodic singular perturbation of a cylindrical waveguide surface may open a gap in the essential spectrum of the Dirichlet problem for the Laplace operator. If the perturbation period is long and the caverns in the cylinder are small, the gap certainly opens. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Omnidirectional circularly polarized slot antenna fed by a cylindrical waveguide in millimeter band

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2007
José Luis Masa-Campos
Abstract A circularly polarized slotted array antenna is presented. The array is fed by a circular waveguide propagating the TM01, to properly generate the required polarization. An omnidirectional azimuth radiation pattern is obtained, as well as a ,10°/+30° elevation antenna coverage. Low losses are achieved because of the waveguide feed. The slot array is mechanized over the metallic wall of the circular waveguide. Furthermore, the antenna presents a solid and rigid mechanical structure, which guarantees an optimum and repetitive response in a manufacturing process. A prototype antenna has been designed and measured. Satisfactory results have been obtained. The slotted array takes part from a signal detection system centered in 36.85 GHz. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 638,642, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22207 [source]

Resonance phenomena in compound cylindrical waveguides

MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 8 2006
Günter Heinzelmann
Abstract We study the large time asymptotics of the solutions u(x,t) of the Dirichlet and the Neumann initial boundary value problem for the wave equation with time-harmonic right-hand side in domains , which are composed of a finite number of disjoint half-cylinders ,1,,,,r with cross-sections ,,1,,,,,r and a bounded part (,compound cylindrical waveguides'). We show that resonances of orders t and t1/2 may occur at a finite or countable discrete set of frequencies ,, while u(x,t) is bounded as t,, for the remaining frequencies. A resonance of order t occurs at , if and only if ,2 is an eigenvalue of the Laplacian ,, in , with regard to the given boundary condition u=0 or ,u/,n=0, respectively. A resonance of order t1/2 occurs at , if and only if (i) ,2 is an eigenvalue of at least one of the Laplacians for the cross-sections ,,1,,,,r, with regard to the respective boundary condition and (ii) the respective homogeneous boundary value problem for the reduced wave equation ,U+,2U=0 in , has non-trivial solutions with suitable asymptotic properties as | x | ,, (,standing waves'). Copyright © 2006 John Wiley & Sons, Ltd. [source]