Browsing by Author "Miyagawa, Hayato"

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Characterization and design of cylindrical microstrip leaky-wave antennas
(2008-07-01)
Lin, Lieh-Chuan
;
Miyagawa, Hayato
;
Kitazawa, Toshihide
;
Hwang, Ruey Bing
;
Lin, Yu-De
The spectral-domain approach is applied for the analysis and the design of the cylindrical microstrip leaky-wave antenna. The first higher-order leaky-mode is thoroughly investigated. We perform the well-known spectral-domain approach and Galerkin's method to acquire the complex propagation constants of leaky modes, which are verified with results obtained by the scattering-parameter extraction technique. Two practical antennas are designed and implemented. Measured return loss and radiation patterns show a good performance of these cylindrical antennas, compared to that of the planar ones.
Simultaneous Determination of Complex Permittivity and Permeability of Columnar Materials With Arbitrarily Shaped Cross Section
(2009-09-01)
Miyagawa, Hayato
;
Wakino, Kikuo
;
Lin, Yu-De
;
Kitazawa, Toshihide
;
電信工程研究所
An effective simultaneous evaluation method for the complex permittivity and permeability of lossy materials is proposed by applying it to an arbitrarily shaped cross-sectional post placed in a rectangular waveguide. We use one sample and only measure S(21) parameters for two different locations of the sample. The measurement of complex reflection parameter S(11) is not required in this evaluation method. The scheme of electromagnetic field analysis for the evaluation is based on the extended spectral-domain approach combined with the mode-matching method, which is accurate and efficient, and can be flexibly used for the iterative fitting operation for the estimation of material parameters. Sample preparation and setting is significantly easier in this method compared to conventional methods. The error caused by deviations in the setting of a sample is investigated. The estimated values for the sample material by this procedure show good agreement with the results obtained using the conventional method over the X-band.