A hybrid RF-acoustic relay is provided where some but not all of the incident RF power is rectified to power the relay and, optionally, to provide power for further link features. The remaining fraction of the incident RF power is used to directly drive an acoustic transceiver array in communication with one or more acoustically powered nodes. In this manner, power, control and communication can be efficiently provided to acoustically powered nodes even in situations where an RF link or an acoustic link would perform poorly.

A hybrid RF-acoustic relay is provided where some but not all of the incident RF power is rectified to power the relay and, optionally, to provide power for further link features. The remaining fraction of the incident RF power is used to directly drive an acoustic transceiver array in communication with one or more acoustically powered nodes. In this manner, power, control and communication can be efficiently provided to acoustically powered nodes even in situations where an RF link or an acoustic link would perform poorly.

In an embodiment, a sub-surface wireless charger includes a transmitter coil and a controller. The controller is configured to generate a protective pulse having a first energy, determine a characteristic of the transmitter coil based on the generated protective pulse, determine whether it is safe to begin wireless charging based on the determined characteristic, and when the controller determines that it is safe to begin wireless charging, generate an operating pulse having a second energy, where the second energy is higher than the first energy.

In an embodiment, a sub-surface wireless charger includes a transmitter coil and a controller. The controller is configured to generate a protective pulse having a first energy, determine a characteristic of the transmitter coil based on the generated protective pulse, determine whether it is safe to begin wireless charging based on the determined characteristic, and when the controller determines that it is safe to begin wireless charging, generate an operating pulse having a second energy, where the second energy is higher than the first energy.

According to various embodiments, provided is an electronic device, which comprises a housing and a relay circuit located inside the housing and is capable of receiving and/or retransmitting an electromagnetic field of an external electronic device, wherein the relay circuit is configured to form a resonant frequency higher than that of an operating frequency range of the electromagnetic field transmitted by the external electronic device. Additional various embodiments are possible.

Described herein are improved configurations for a wireless power transfer. The parameters of components of the wireless energy transfer system are adjusted to control the power delivered to the load at the device. The power output of the source amplifier is controlled to maintain a substantially 50% duty cycle at the rectifier of the device.

An antenna include a resonator element configured to radiate a wireless signal and a substrate embedding the resonator. The resonator element may be a 3D resonator element. The 3D resonator element may be a helical resonator element.

A repeater may comprise: a first member; and at least one pattern formed on the first member and configured to provide at least one of an electric field and a magnetic field, which is incident from a wireless power transmitter onto a first surface of the first member, through a second surface of the first member, opposite to the first surface.

A repeater may comprise: a first member; and at least one pattern formed on the first member and configured to provide at least one of an electric field and a magnetic field, which is incident from a wireless power transmitter onto a first surface of the first member, through a second surface of the first member, opposite to the first surface.

One example discloses a near-field communications device, including: an energy harvesting circuit configured to be coupled to a near-field antenna that is responsive to non-propagating quasi-static near-field energy; wherein the harvesting circuit is configured to harvest energy from the non-propagating quasi-static near-field energy; and wherein the harvesting circuit includes a harvesting filter configured to input a first set of near-field energy and output a second set of near-field energy; and wherein the second set of near-field energy is a sub-set of the first set of near-field energy.