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Circular Waveguide (circular + waveguide)

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Engineering	100%

Selected Abstracts

Propagation characteristic analysis of ridged circular waveguide using 2D finite-difference frequency-domain method

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 3 2005
Qi Zhang
Abstract The propagation characteristics of ridged circular waveguides are analyzed by using 2D finite-difference frequency-domain (2D FDFD). Based on the 2D FDFD method in a cylindrical coordinate system, general difference formulas for the ridged circular waveguide are deduced, and modified difference formulas are built at some special points of the ridged circular waveguides. To verify the proposed method, three ridged circular waveguide structures are investigated and the numerical results are compared with available ones obtained by other research methods. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE 15, 2005. [source]

Analysis of electromagnetic band-gap waveguide structures using body-of-revolution finite-difference time-domain method

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2007
Ming-Sze Tong
Abstract Study of electromagnetic band-gap (EBG) structures has become a hot topic in computational electromagnetics. In this article, some EBG structures integrated inside a circular waveguide are studied. They are formed by a series of air-gaps within a circular dielectric-filled waveguide. A body-of-revolution finite-difference time-domain (BOR-FDTD) method is adopted for analysis of such waveguide structures, due to their axial symmetric properties. The opening ends of the waveguide are treated as a matched load using an unsplit perfectly matched layer technique. Excitations on a waveguide in BOR-FDTD are demonstrated. Numerical results of various air-gap lengths with respect to the period of separation are given, showing an interesting tendency of EBG behavior. A chirping-and-tapering technique is applied on the EBG pattern to improve the overall performance. The proposed EBG structures may be applied into antenna structures or other system for unwanted signal suppression. Results show that the BOR-FDTD offers a good alternative in analyzing axial symmetric configurations, as it offers enormous savings in computational time and memory comparing with a general 3D-FDTD algorithm. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2201,2206, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22668 [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]

Analysis of circular waveguides with soft and hard surfaces realized by strip-loaded walls using asymptotic boundary conditions

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 6 2001
Ahmed A. Kishk
Abstract Soft and hard walls are realized for a circular waveguide with walls coated by a uniform dielectric layer of appropriate thickness and loaded with conducting strips. The strips are oriented along the waveguide axis (z -axis) for hard surfaces or ,-directed for soft surfaces in a periodic form. The simple approximate asymptotic strip boundary condition (ASBC) is used to analyze the structure. For the dominant mode, when the waveguide walls are hard or soft, a linear field distribution across the waveguide cross section can be obtained. Then the waveguide can be used as an antenna with good linear polarization. The characteristics of such waveguides are presented with sample radiation patterns as compared with hollow waveguide radiation patterns. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 433,436, 2001. [source]

The computation of the input impedance of a biconical antenna by means of a method of segmentation based on 3D finite elements

INTERNATIONAL JOURNAL OF NUMERICAL MODELLING: ELECTRONIC NETWORKS, DEVICES AND FIELDS, Issue 5 2003
José Ma Gil
Abstract The analysis of structures with complex geometries leads to the use of three-dimensional numerical methods. Such devices can be unmanageable unless a segmentation technique is applied. In this work, a hybrid 3D finite-element-mode matching method, based on the generalized admittance matrix (GAM) is applied to the computation of the input impedance of a biconical antenna fed by a cylindrical cavity loaded with resonant slots and matched by a coupling network composed of three multi-ridge circular irises and sections of circular waveguides. The structure is segmented into regions which are analysed separately and, by means of linking the partial matrices calculated, the generalized scattering matrix (GSM) is obtained. In order to validate the method, numerical results and measurements are compared. Copyright © 2003 John Wiley & Sons, Ltd. [source]