In this article, the formulation of dispersive characteristics associated with an electronic polarization is discussed. The formulation is appropriate for use in the finite‐difference‐time‐domain (FD‐TD) method and is based on the equation of polarization. The validity of the formulation is verified by comparing the calculated complex dielectric constant with analytical values.

SUMMARYDielectric resonator antennas (DRAs) are a relatively new class of antenna that utilizes the radiation phenomena of dielectric resonators in open space. Since mainly analytical approaches have been applied to investigate DRA designs, the current DRA forms are limited to simple geometric shapes and highperformance DRAs with complex shapes have not yet been developed. Topology optimization is capable of yielding high-performance structures, and has been extensively applied to a variety of structural optimization problems. Applying it to the task of DRA design may be extremely useful for the design of high-performance antennas. On the other hand, the finite difference time domain (FDTD) method has been used to numerically evaluate general antenna performance, since it is numerically robust during time domain analyses and can handle complex models. Thus, the integration of topology optimization with the FDTD method has the potential to enable innovative designs of advanced antennas that offer exceptional performance. In this research, we propose a new topology optimization method for the design of DRAs that aim to operate with enhanced bandwidths, using the FDTD method. First, the concept of topology optimization is briefly discussed, and a way to integrate topology optimization with the FDTD method is proposed. Next, design requirements are clarified and the corresponding objective functions and the optimization problem are formulated. An optimization algorithm is constructed based on these formulations. Finally, several DRA design examples are presented to confirm the usefulness of the proposed method.

The three‐dimensional time‐domain formulation for dispersive media which obey Cole‐Cole's circular arc law is presented using the finite‐difference‐time‐domain (FD‐TD) technique. The validity of the formulation is verified by comparing the calculated complex dielectric constant to analytical values.

A new complex, [Re(6)S(8)Cl(5)ppy](3-) (ppy = 4-phenylpyridine), was synthesized and characterized. The complex showed red emission at 296 K in both the crystalline phase and CH(3)CN. The transient absorption spectrum of [Re(6)S(8)Cl(5)ppy](3-) revealed that the emissive excited state involved the {Re(6)(μ(3)-S)(8)} core-to-ligand charge-transfer character.

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