A radio-frequency (RF) transformer includes a ferrite core defining a bore therethrough. The RF transformer also includes a first wire and a second wire. The first and second wires are twisted and form a first exterior half loop at least partially around an exterior of the ferrite core. The first wire, but not the second wire, forms a second exterior half loop at least partially around the exterior of the ferrite core. The ferrite core is configured to provide a primarily magnetic coupling for signals having a frequency that is less than a predetermined threshold. The first and second wires are configured to provide a primarily capacitive coupling for signals having the frequency that is greater than the predetermined threshold.

The device comprises an annular guide component (1) that defines a central space (5) for accommodating the toroidal magnetic core (4) and comprises a plurality of channels (2) for receiving parts of a wire that form turns (3) of said toroidal coil upon arrangement about the toroidal magnetic core (4), said channels (2) being arranged transversely, from end face to end face of the annular guide component (1), distributed over an interior annular wall (1i) and separated from one another in accordance with a predetermined order. The method comprises use of the device of the invention for forming a toroidal coil comprising one or more windings.

The device comprises an annular guide component (1) that defines a central space (5) for accommodating the toroidal magnetic core (4) and comprises a plurality of channels (2) for receiving parts of a wire that form turns (3) of said toroidal coil upon arrangement about the toroidal magnetic core (4), said channels (2) being arranged transversely, from end face to end face of the annular guide component (1), distributed over an interior annular wall (1i) and separated from one another in accordance with a predetermined order. The method comprises use of the device of the invention for forming a toroidal coil comprising one or more windings.

An RF transformer is provided. The RF transformer includes a ferrite core and a winding coil structure formed around the ferrite core. The winding coil structure is in electrical contact with a center portion of the ferrite core. The winding coil structure is essentially electrically and physically spaced from external portions of the ferrite core.

An RF transformer is provided. The RF transformer includes a ferrite core and a winding coil structure formed around the ferrite core. The winding coil structure is in electrical contact with a center portion of the ferrite core. The winding coil structure is essentially electrically and physically spaced from external portions of the ferrite core.

A wire wound-type coil component with an integrated structure does not have a bonding portion where there is concern about reliability with respect to a spiral conductive wire, a terminal electrode, and an annular core. A coil component includes a core with an integrated structure, at least part of which is a winding core portion, which has an annular shape having a through-hole, and which is made of a non-conductive material; and a coil conductor with an integrated structure, which has a spiral conductive wire arranged to spirally extend around the winding core portion and first and second terminal electrodes formed at both end portions of the spiral conductive wire, respectively. The coil component is manufactured through three-dimensionally shaping the core, the coil conductor, and a shape holding member for holding a shape of a wall surface of the core defining the through-hole, by using a 3D printer.

An apparatus for magnetic field compression includes a toroid and a plurality of separate coils wound around the toroid. The coils are spaced about a circumference of the toroid and each coil generates a magnetic field in response to electric current flowing in the coil. The toroid and a group of the coils each include a size that respectively gradually decreases over a predetermined portion of the toroid. The magnetic field is compressed or has a highest magnetic flux density proximate a central region of the coils around the toroid.

An apparatus for magnetic field compression includes a toroid and a plurality of separate coils wound around the toroid. The coils are spaced about a circumference of the toroid and each coil generates a magnetic field in response to electric current flowing in the coil. The toroid and a group of the coils each include a size that respectively gradually decreases over a predetermined portion of the toroid. The magnetic field is compressed or has a highest magnetic flux density proximate a central region of the coils around the toroid.

A winding device includes a winding core configured to take up a wire, wherein the winding core includes an inner winding core configured to be rotated by a rotating part and an outer winding core configured to surround the inner winding core and rotate together with the inner winding core.

Transformers having a plurality of windings from a single Litz wire, as well as systems including such transformers and methods of providing such transformers are disclosed. A transformer includes a core and a single Litz wire having a plurality of individual strands of conductive material. The plurality of individual strands of conductive material are separated into a plurality of groups, each one of the plurality of groups being a winding of the transformer such that the transformer comprises a plurality of windings.