FD-TD Analysis of Coaxial Probes Inserted into Rectangular Waveguides

Atsushi SANADA  Minoru SANAGI  Shigeji NOGI  Kuniyoshi YAMANE  

IEICE TRANSACTIONS on Electronics   Vol.E81-C   No.12   pp.1821-1830
Publication Date: 1998/12/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Computational Electromagnetics)
coaxial probe,  waveguide-coaxial transition,  FD-TD method,  field concentration,  evanescent mode,  

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Full-wave FD-TD analysis has been carried out for coaxial probes inserted into waveguides. Both single and symmetrically placed paired coaxial probe structures have been discussed and we have revealed the relation between equivalent circuit parameters and structural parameters of the coaxial probes including cases for large diameter and extension length, which is useful for practical waveguide circuit design. The equivalent circuit parameters calculated from the scattering parameters agreed well with corresponding measured data. From the calculated field in a waveguide, field concentration at sharp edges of probe sole or base, which ought to be taken into account for high power application design has been also discussed. Besides, amplitudes of higher order modes in waveguides excited by coaxial probes or pairs of coaxial probes has been calculated so as to estimate the range beyond which higher order modes decay sufficiently. This estimation is necessary for simple and easy design of probe using circuit theory.