Toyomitsu S., Nagayama T., Fukushima S., Watanabe T. . Two Types of Composite T-/π-Type Rhombic Unit Cell Structures for Topological Waveguides . 2025 Asia-Pacific Microwave Conference2025 · 担当区分： 責任著者 記述言語： 英語 掲載種別： 研究論文（国際会議プロシーディングス） 出版者・発行元： Asia Pacific Microwave Conference Proceedings APMC Two types of composite T-/π-type rhombic unit cell structures are presented for the design of topological waveguides. These are structures composing of T-/π-type circuits and have gaps on either of those, and their periodicities are mutually shifted by half-period so that the frequency dispersion characteristics and bandgaps are identical. The characteristics are shown from the results of the eigenvalue analysis. A topological waveguide is constituted using the proposed unit cell structures, and the operations at microwave frequencies are validated by calculating the electric field distributions with the full-wave simulations. The results indicate the concentration of the electric field on the topological waveguide. DOI： 10.1109/apmc65046.2025.11378974 Scopus
Nagayama T. . Four Two-Dimensional Rhombic Distributed Transmission-Line Models Related by 90-Degree Rotations for Topological Waveguides . 2025 IEEE International Symposium on Radio-F2025 · 担当区分： 筆頭著者, 最終著者, 責任著者 記述言語： 英語 掲載種別： 研究論文（国際会議プロシーディングス） 出版者・発行元： 2025 IEEE International Symposium on Radio Frequency Integration Technology Rfit 2025 Proceedings Four two-dimensional rhombic distributed transmission-line models related by 90-degree rotations for topological waveguides are presented. The formulas to calculate the dispersion characteristics are derived and it is shown from the calculation results with the formulas that the frequency ranges of those bandgaps including the operating bands as topological waveguides agree with each other. An electromagnetic topological waveguide and an acoustic one are constituted by periodically arranging the proposed models and the operations are validated by a SPICE simulation. The calculated results show the voltage concentration along the topological waveguide. DOI： 10.1109/rfit65667.2025.11364602 Scopus
Nagayama T. . Constitutive Method for Topological Waveguides Using Two-Dimensional T- and π-Type Rhombic Unit Cell Structures . 2025 International Symposium on Antennas and Propagation2025 · 担当区分： 筆頭著者, 最終著者, 責任著者 記述言語： 英語 掲載種別： 研究論文（国際会議プロシーディングス） 出版者・発行元： 2025 International Symposium on Antennas and Propagation Isap 2025 The constitutive method for topological waveguides is presented based on the theory of T- and π-type circuits. Two-dimensional T- and π-type rhombic unit cell structures without passive resonant components, whose periods are mutually shifted by half-period, are proposed, and it is shown from the results by eigenvalue analysis that those dispersion characteristics and frequency bandgaps agree well with each other. A topological waveguide is constituted using the proposed unit cell structures and the operation is demonstrated by full-wave simulations. DOI： 10.23919/isap63122.2025.11362240 Scopus
