We reveal the existence of a new type of surface electromagnetic waves supported by hyperbolic metasurfaces, described by a conductivity tensor with an indefinite signature. We demonstrate that the spectrum of the hyperbolic metasurface waves consists of two branches corresponding to hybrid TE-TM waves with the polarization that varies from linear to elliptic or circular depending on the wave frequency and propagation direction. We analyze the effect of losses of the surface waves and derive the corresponding analytical asymptotic expressions.
Since the beginning of the 20th century, researchers have been looking for an effective way to transfer power without wired connections, but the wireless power transfer technology started to attract extensive interest from the industry side only in 2007 when the first smartphone was released and a consumer electronics revolution was triggered. Currently, the modern technology of wireless power transfer already has a rich research and development history as well as outstanding advances in commercialization. This review is focused on the description of distinctive implementations of this technology inspired by the modern trends in electrodynamics. We compare the performances of the power transfer systems based on three kinds of resonators, i.e., metallic coil resonators, dielectric resonators, and cavity mode resonators. We argue that metamaterials and meta-atoms are powerful tools to improve the functionalities and to obtain novel properties of the systems. We review different approaches to enhance the functionality of the wireless power transfer systems including control of the power transfer path and increase of the operation range and efficiency. Various applications of wireless power transfer are discussed and currently available standards are reviewed.
Metasurfaces have been investigated and its numerous exotic functionalities and the potentials to arbitrarily control of the electromagnetic fields have been extensively explored. However, only limited types of metasurface have finally entered into real products. Here, we introduce a concept of a metasurface-based smart table for wirelessly charging portable devices and report its first prototype. The proposed metasurface can efficiently transform evanescent fields into propagating waves which significantly improves the near field coupling to charge a receiving device arbitrarily placed on its surface wirelessly through magnetic resonance coupling. In this way, power transfer efficiency of 80% is experimentally obtained when the receiver is placed at any distances from the transmitter. The proposed concept enables a variety of important applications in the fields of consumer electronics, electric automobiles, implanted medical devices, etc. The further developed metasurface-based smart table may serve as an ultimate 2-dimensional platform and support charging multiple receivers.
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