A three-dimensional finite-difference time-domain (FDTD) program has been developed to provide a numerical solution for light scattering by nonspherical dielectric particles. The perfectly matched layer (PML) absorbing boundary condition (ABC) is used to truncate the computational domain. As a result of using the PML ABC, the present FDTD program requires much less computer memory and CPU time than those that use traditional truncation techniques. For spheres with particle-size parameters as large as 40, the extinction and absorption efficiencies from the present FDTD program match the Mie results closely, with differences of less than approximately 1%. The difference in the scattering phase function is typically smaller than approximately 5%. The FDTD program has also been checked by use of the exact solution for light scattering by a pair of spheres in contact. Finally, applications of the PML FDTD to hexagonal particles and to spheres aggregated into tetrahedral structures are presented.

A three-dimensional unconditionally-stable locally-one-dimensional finite-difference time-domain (LOD-FDTD) method is proposed and is proved unconditionally stable analytically. In it, the number of equations to be computed is the same as that with the conventional three-dimensional alternating direction implicit FDTD (ADI-FDTD) but with reduced arithmetic operations. The reduction in arithmetic operations leads to approximately 20% less computational time in comparisons with the ADI-FDTD method.Index Terms-Alternating direction implicit finite-difference time-domain (ADI-FDTD), Courant Friedrich Levy (CFL) limit, FDTD, locally-one-dimensional finite-difference time-domain (LOD-FDTD), unconditionally stable.

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A fully planar wireless power transfer (WPT) system via strongly coupled magnetic resonances is presented. In it, both the transmitter and the receiver are planarized with the use of coplanar printed spiral coils (PSCs) and a printed loop. An equivalent circuit model of the proposed planar WPT system is derived to facilitate the design, and a flowchart is provided for the optimization of the system with given size constraints. To realize high peak power transfer efficiency, the quality factor of individual loop or resonator, the mutual coupling between resonators, and the frequency splitting phenomenon of the system are analyzed in addition to the effect of the input impedance of the system on the transmission efficiency. Furthermore, parallel current paths are created by applying auxiliary strips to the backside of the substrates and connecting to the prime resonators using vias to decrease the resistance and to increase the quality factor of the PSC resonators, and this in turn further improves the transfer efficiency of the proposed planar WPT system. The measured results show that the proposed WPT system is able to provide a stable wireless power transfer with up to 81.68% efficiency at a distance of 10 cm. The planar structure and the high transfer efficiency make the proposed design a suitable candidate for wireless power transfer of small portable electronic devices.

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A new design CPW-fed printed semifractal antenna with arc-line feed for RFID reader applications is presented. The proposed antenna comprised of a conjunction of coplanar waveguide and microstrip feed line, a semifractal patch, which is usable for RFID reader frequency bands. By embedding a semifractal patch, multiresonance characteristics at 3.8, 5.8, 8.2, and 9.7 GHz frequencies are obtained.

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