A magnetic field is formed at a predetermined region. A magnetic field formation device configured to generate a variable magnetic field at a predetermined region A includes: at least one power supplying resonator configured to generate the variable magnetic field; and power-supplying coils configured to generate an induced current in the at least one power supplying resonator, all of the power-supplying coils and the at least one power supplying resonator being disposed so that coil surfaces oppose the predetermined region A, and at least one of the power-supplying coils being disposed to have a coil surface direction which intersects with coil surface directions of the other power-supplying coils.

According to a first aspect of the present disclosed subject matter, a dynamic calibration method in a system comprising a relay, having a coil, adapted to inductively transfer power for charging a device and a transmitter, having a coil and a controller configured to inductively transmit to the relay the power for charging the device, wherein the transmitter and the relay are separated by a medium, the method comprising: determining operating parameters selected from a group consisting of minimal and maximal operating frequency; direction of power increase relative to operating frequency; minimal and maximal duty cycle; minimal and maximal operating amplitude; and any combination thereof; wherein the operating parameters and a ping frequency are determined based on dynamic measurements of the transmitter operation and calculations executed by the controller during the calibration.

According to a first aspect of the present disclosed subject matter, a dynamic calibration method in a system comprising a relay, having a coil, adapted to inductively transfer power for charging a device and a transmitter, having a coil and a controller configured to inductively transmit to the relay the power for charging the device, wherein the transmitter and the relay are separated by a medium, the method comprising: determining operating parameters selected from a group consisting of minimal and maximal operating frequency; direction of power increase relative to operating frequency; minimal and maximal duty cycle; minimal and maximal operating amplitude; and any combination thereof; wherein the operating parameters and a ping frequency are determined based on dynamic measurements of the transmitter operation and calculations executed by the controller during the calibration.

An electric power transmission device transmits electric power to an electric power reception device including an electric power reception coil in water. The electric power transmission device includes one or more transmission coils which include an electric power transmission coil configured to transmit electric power to the electric power reception coil via a magnetic field, an electric power transmitter, configured to transmit AC power to the electric power transmission coil, a capacitor which is connected to the transmission coil and forms a resonance circuit which resonates with the transmission coil, a first tubular member which is waterproof and seals a periphery of the transmission coil, a second tubular member which surrounds the first tubular member and includes a plurality of holes, and an adjuster, configured to adjust an amount of air in a gap between the first tubular member and the second tubular member.

According to a first aspect of the present disclosed subject matter, a system for wirelessly charging a device, having a built-in coil, via a medium comprising: at least one relay adapted to inductively transfer power for charging the device; and a transmitter configured to inductively transmit to the at least one relay the power for charging the device, wherein the transmitter and the relay are separated by the medium and wherein the relay and the transmitter substantially face each other; wherein the transmitter further comprises a transmitter coil and a transmitter capacitor constituting a transmitter resonance circuit, wherein the relay further comprises a relay coil and a relay capacitor constituting a relay resonance circuit, and wherein a joint resonance frequencies (JRF) of both resonance circuits have a main resonance frequency (MRF); and wherein the transmitter operates at an operational frequency (OPF) selected from a range of OPFs, wherein the range of OPFs is substantially different than the MRF.

A wireless power transfer system is disclosed. The system includes a first resonator having a first resonant frequency .sub.o1, a half power bandwidth .sub.1, and an unloaded quality factor Qo.sub.1=.sub.o1/.sub.1 coupled through a first coupling circuit to a power source, a second resonator having a second resonant frequency .sub.o2, a half power bandwidth .sub.2, and an unloaded quality factor Qo.sub.2=.sub.o2/.sub.2 coupled through a second coupling circuit to a load, the first resonator disposed a distance away from the second resonator, wherein the distance is smaller than the first and second resonant wavelengths, the first and second coupling circuits are configured so that up to a maximum achievable power transfer efficiency between the first and second resonators can be achieved, wherein Qo.sub.1 and Qo.sub.2 can be less than 100.

A wireless power transfer system is disclosed. The system includes a first resonator having a first resonant frequency .sub.o1, a half power bandwidth .sub.1, and an unloaded quality factor Qo.sub.1=.sub.o1/.sub.1 coupled through a first coupling circuit to a power source, a second resonator having a second resonant frequency .sub.o2, a half power bandwidth .sub.2, and an unloaded quality factor Qo.sub.2=.sub.o2/.sub.2 coupled through a second coupling circuit to a load, the first resonator disposed a distance away from the second resonator, wherein the distance is smaller than the first and second resonant wavelengths, the first and second coupling circuits are configured so that up to a maximum achievable power transfer efficiency between the first and second resonators can be achieved, wherein Qo.sub.1 and Qo.sub.2 can be less than 100.

A wireless power transmission system and communication system is disclosed. A wireless power transmission system and communication system according to an embodiment of the present invention comprises: a transmission part which includes a first surface wave antenna, installed in a metal wall, for transmitting and receiving an electromagnetic surface wave flowing along a surface of the metal wall, and a first monopole antenna connected to the first surface wave antenna in parallel; and a reception part which includes at least one of a second monopole antenna and a second surface wave antenna, installed in a space partitioned by the metal wall, for receiving an electromagnetic surface wave flowing along the surface of the metal wall.

A wireless power transmission system and communication system is disclosed. A wireless power transmission system and communication system according to an embodiment of the present invention comprises: a transmission part which includes a first surface wave antenna, installed in a metal wall, for transmitting and receiving an electromagnetic surface wave flowing along a surface of the metal wall, and a first monopole antenna connected to the first surface wave antenna in parallel; and a reception part which includes at least one of a second monopole antenna and a second surface wave antenna, installed in a space partitioned by the metal wall, for receiving an electromagnetic surface wave flowing along the surface of the metal wall.

A wireless power transmission device includes a contactless transmitter unit, a contactless receiver unit and a step-down transformer. The transmitter unit receives an input AC power. A receiver coil of the receiver unit and a transmitter coil of the transmitter coil are electromagnetically coupled with each other. The input AC power is electromagnetically coupled to the receiver coil through the transmitter coil. Consequently, the input AC power is converted into a first output AC power. A first coil and a second coil of the step-down transformer are electromagnetically coupled with each other. The first coil is electrically connected with the receiver coil to receive the first output AC power. A second output AC power is outputted from the second coil. A turn ratio of the first coil to the second coil is larger than a turn ratio of the transmitter coil to the receiver coil.