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A key limitation inherent in wireless power transmission (WPT) systems using coils is a high sensitivity to the alignment between the transmitting and receiving coils. Moreover, the physical separation of the transmitting and receiving coils or any metallic barrier between them can notably reduce the efficiency. To overcome these limitations, a practical WPT system that is insensitive to the alignment between coils and metallic obstacles is proposed. It uses a printed circuit board-type antenna fabricated by reducing the structure of an antenna used in previous research and is designed to resonate at the target frequency through impedance matching. The proposed system uses surface-guided-mode resonance at the metal–air interface and transmits uniform power within 1.3 m. In addition, the proposed system satisfies the electromagnetic field international standard that is the electric field and magnetic field reference values are 152.5 V/m and 0.4 A/m, respectively at 4 MHz.

We present a metasurface antenna comprising periodic arrangement of interconnected rectangular unit cells. The proposed antenna is designed to utilize evanescent mode resonance. The resonance is achieved by utilizing strong cavity mode oscillation, when the antenna is placed over a metallic surface. However, when the antenna is freely suspended in the air, in its natural state, the resonance is absent. At an optimized feed point, the antenna can be excited directly with a 50 ohm impedance line.

In this paper, we proposed a magnetic field wireless power transmission antenna using ferrite. In the past, additional grounding enabled magnetic field wireless power transmission, enabling the magnetic field wireless power transmission without additional grounding by using the characteristics of ferrite. Ferrite has the effect of shielding the magnetic field and reduces the leakage power to increase the transmission efficiency. We propose an antenna for magnetic field wireless power transmission using ferrite and confirm that it is transmitted by 5W magnetic field wireless power through experiments. The wireless power transmission proposed in this paper can be applied variously to the Internet of things by the magnetic field wireless power transmission through the metal.

In the present work, we demonstrate controlling the excitation of bright mode (continuum mode) resonance and dark mode (discrete mode) resonance in a planar metasurface made of sinusoidal modulation inside a closed rectangular metallic ring placed over a dielectric substrate. Unlike asymmetrical breaking of a meta-atom (often referred to as the unit cell) to achieve the dark mode response in regular metamaterials, in the present structure, the bright or dark mode resonance is achieved using even or odd half cycle modulation. The achieved dark-mode shows a sharp resonance for a particular polarization of the incident electric field, which results in an electromagnetically induced transparency like spectrum. The electromagnetic behavior of the proposed meta-atom has been investigated in the frequency domain using commercially available software and validated through experiments in the gigahertz regime.