Topological wireless power transfer (TWPT) arrays provide directional power transfer, which are robust to external disturbances. Often realized as a chains of dimers, the ability to adjust the coupling between constituent resonator elements is an important means of establishing necessary conditions for power transfer. This paper explores the coupling interactions that are possible within dimers consisting of paired split-ring resonators (SRRs) in close proximity. Transfer efficiencies and through impedances are computationally studied for various rotational orientations of edge-and broadside-coupled SRRs. The obtained results reveal that relative rotational orientation can be employed as a sensitive design parameter to provide a variety of high- and low-coupling options within and between SRR dimers, with different power transfer efficiency implications.

This paper presents the numerical study of a polarization-insensitive energy harvesting metasurface. The proposed metasurface is designed to harvest ambient electromagnetic (EM) energy at 2.45 GHz. The basic constituent element of the metasurface is an electric-field-coupled (ELC) resonator, which is used to synthesize a 2 x 2 super-cell with polarization-insensitive features. Finally, the metasurface is realized as a 3 x 3 array of ELC super-cells, and presents an energy harvesting efficiency of 95.4% at 2.45 GHz. The achieved energy harvesting efficiency is maintained irrespective of the polarization of the incident excitation. The proposed metasurface configuration holds promise for the implementation of ambient EM harvesters, able to scavenge energy from wireless technologies operating in the 2.45 GHz band.

This paper presents the design of a fractal unit cell absorber for electromagnetic energy absorption in the 2.45 GHz band. The configuration is based on a second-order Minkowski-inspired fractal geometry, through which a compact structure is realized. The proposed design is achieved using full-wave electromagnetic simulations and the study of an equivalent circuit model. At 2.45 GHz, the synthesized structure achieves a near-perfect absorptivity of 99%, with a modest footprint of 0.11λ. The realized structure can serve as a constituent element for the design of absorber arrays to mitigate multipath effects and prevent eavesdropping attacks in indoor wireless environments.