An antenna device incorporated in an electronic apparatus to communicate with an external apparatus via an electromagnetic field signal includes a first conductor provided inside a housing of the electronic apparatus and opposing the external apparatus, a loop antenna having an antenna coil conductively coupled to the external apparatus and coiling thereon, a sheet-like second conductor provided as being spaced with a predetermined space from the first conductor and partially overlapping or making contact with a surface of the loop antenna opposite to a surface opposing the external apparatus, and a sheet-like third conductor provided between the first conductor and the second conductor and having one end overlapping or making contact with the first conductor and other end partially overlapping or making contact with the second conductor.

A coil antenna is mounted on a circuit substrate. A wiring pattern is disposed on the circuit substrate and connects the coil antenna and a feed circuit. A conductive pattern is disposed on the circuit substrate and located outside a region surrounded by the coil antenna, feed circuit, and wiring pattern. A conductive pattern is disposed on the circuit substrate and located inside the region surrounded by the coil antenna, feed circuit, and wiring pattern. Connection conductors connect the conductive pattern and conductive pattern and are disposed on the circuit substrate. The connection conductor includes interlayer connection conductors.

Radio frequency (RF) isolators are described, coupling circuit domains operating at different voltages. The RF isolator may include a transmitter which emits a directional signal toward a receiver. Layers of materials having different dielectric constants may be arranged to confine the emission along a path to the receiver. The emitter may be an antenna having an aperture facing the receiver.

An antenna device includes a base and a coil element that includes a coil conductor, first and second terminals respectively connected to first and second ends of the coil conductor, and third and fourth terminals extended from a secondary coil conductive portion of the coil conductor. First, second, third, and fourth electrodes and a radiating conductor are disposed on the base. The first electrode is connected to the first terminal and links to a power feed circuit. The second electrode is connected to the second terminal and links to the power feed circuit. The third electrode is connected to the third terminal. The fourth electrode is connected to the fourth terminal. The radiating conductor links to the third electrode and the fourth electrode. The coil element and the radiating conductor are magnetically coupled to a communication-partner antenna.

In an antenna circuit including an antenna 1 and an antenna 2 that is connected in series with the antenna 1 and includes inductance, a variable capacitor C.sub.v and a variable resistor R.sub.v connected in parallel with the antenna 2 are provided. This enables controlling of an actual amplitude ratio r and a phase difference between currents I.sub.1 and I.sub.2 flowing through the two antennas 1 and 2 into desired values. Flows of the currents I.sub.1 and I.sub.2 with the phase difference through the antennas 1 and 2 enable forming of a favorable communication area. In addition, setting of the actual amplitude ratio r between the currents I.sub.1 and I.sub.2 flowing through the antennas 1 and 2 to a value other than 1 enables forming of an asymmetric communication area.

A communications device includes an antenna including a radiator and a ground. A NFC circuit and the radiator are coupled at a first node; a non-NFC circuit and the radiator are coupled at a second node by using a non-NFC feeding path, the non-NFC feeding path includes two capacitors with different capacitances. The radiator forms a first part between the first node and the second node. The radiator includes a second part, one end of the second part is coupled to the ground, and the other end is connected to the first part. An electrical length of the second part is less than a quarter wavelength corresponding to a resonance frequency of a low frequency signal, and the electrical length of the second part is greater than an electrical length of the first part. The radiator includes a third part from the first node to an endpoint of the radiator.

In an antenna circuit including an antenna 1 and an antenna 2 that is connected in series with the antenna 1 and includes inductance, a variable capacitor C.sub.v and a variable resistor R.sub.v connected in parallel with the antenna 2 are provided. This enables controlling of an actual amplitude ratio r and a phase difference between currents I.sub.1 and I.sub.2 flowing through the two antennas 1 and 2 into desired values. Flows of the currents I.sub.1 and I.sub.2 with the phase difference through the antennas 1 and 2 enable forming of a favorable communication area. In addition, setting of the actual amplitude ratio r between the currents I.sub.1 and I.sub.2 flowing through the antennas 1 and 2 to a value other than 1 enables forming of an asymmetric communication area.

One example discloses a near-field device, configured to receive a non-propagating quasi-static near-field signal from a near-field antenna, comprising: a tuning circuit including a set of impedance tuning banks; and a controller configured to, identify a set of impedance values for the impedance tuning banks corresponding to an initial resonance frequency, bandwidth and/or quality factor of the near-field antenna and near-field device combination; detect a change in the resonance frequency, bandwidth and/or quality factor; access a pre-stored set of specific resonance frequency, bandwidth and/or quality factor changes corresponding to a set of specific conductive structures; identify a conductive structure from the set of conductive structures corresponding to the detected change; access a pre-stored set of specific near-field device actions corresponding to the set of conductive structures; and effect a set of specific actions from the set of near-field device actions corresponding to the identified conductive structure.

A semiconductor device of the present invention is provided with a plurality of memory chips laminated to each other, each of said memory chips having: a first transmission/reception coil for communication by means of inductive coupling; first lead-out lines led out from both ends of the first transmission/reception coil; and a first transmission/reception circuit, which is connected to the first lead-out lines, and which inputs/outputs signals to/from the first transmission/reception coil. The semiconductor device is also provided with an interposer, which is disposed on one end in the laminating direction of the memory chips, and which has, for each of the memory chips: a second transmission/reception coil coupled to the first transmission/reception coil by means of inductive coupling; second lead-out lines led out from both ends of the second transmission/reception coil; and a second transmission/reception circuit, which is connected to the second lead-out lines, and which inputs/outputs signals to/from the second transmission/reception coil. The memory chips are disposed at positions where, in plan view, the first transmission/reception circuits overlap each other, and the first transmission/reception coils are disposed around the first transmission/reception circuits, said first transmission/reception coils being disposed at positions where the first transmission/reception coils do not overlap each other.

A small antenna device having good communications performance and a wide communications area even when a metal plate is present in the antenna communications direction, even when the antenna is arranged, for example, inside a box-shaped metal case, and even when a through hole is used that has a smaller area than the antenna. This device comprises: the antenna; a rear surface cover overlapping with the antenna and being a conductor that faces the winding of the antenna; two first insulating areas provided in the rear surface cover and extending in a direction that intersects the winding axis of the antenna; and a second insulating area that connects between the first insulating areas. At least part of the area sandwiched by the first insulating areas faces the antenna.