Higher order mode impedances and cut-off frequencies of overmoded coaxial waveguides

Autor:	J. G. Davis, Andrew Gibson
Rok vydání:	2006
Předmět:	Engineering business.industry Input impedance Cutoff frequency Characteristic impedance Transverse mode Superposition principle Optics Physics::Accelerator Physics Electrical and Electronic Engineering Antenna (radio) Coaxial business Electrical impedance
Zdroj:	International Journal of Electronics. 93:335-346
ISSN:	1362-3060 0020-7217
DOI:	10.1080/00207210500429077
Popis:	Using both theoretical and experimental methods the critical geometrical ratios for effective higher order mode superposition in coaxial waveguides are identified for SDMA beam forming antenna applications. Higher order mode impedances are also important in the design of such antennas and a closed form expression for the power-voltage definition of impedance is derived together with estimates for the voltage-current and power-current forms. An industry standard finite element solver is used to confirm the accuracy of these formulations for a 60 mm radius overmoded coaxial waveguide. In the second part of the paper, the mode chart is used to design a coaxially fed, overmoded air-spaced coaxial waveguide “T” junction supporting the TEM, TE 11 and TE 21 modes. A Green's function based model of the input impedance of this junction establishes that the power-voltage characteristic impedance occurs naturally in calculations requiring absolute impedance values. Finally, this input impedance model, which includes...
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::ae0c70a861731d766bb2d8eb184ddddc https://doi.org/10.1080/00207210500429077 Zobrazit plný text záznamu