Provided are a core electric wire for multi-core cable that is superior in flex resistance at low temperature, and a multi-core cable employing the same. A core electric wire for multi-core cable according to an aspect of the present invention comprises a conductor obtained by twisting element wires, and an insulating layer that covers an outer periphery of the conductor, in which, in a transverse cross section of the conductor, a percentage of an area occupied by void regions among the element wires is from 5% to 20%. An average area of the conductor in the transverse cross section is preferably from 1.0 mm.sup.2 to 3.0 mm.sup.2. An average diameter of the element wires in the conductor is preferably from 40 m to 100 m, and the number of the element wires is preferably from 196 to 2,450. The conductor is preferably obtained by twisting stranded element wires obtained by twisting subsets of element wires. The insulating layer preferably comprises as a principal component a copolymer of ethylene and an -olefin having a carbonyl group.

Provided are a core electric wire for multi-core cable that is superior in flex resistance at low temperature, and a multi-core cable employing the same. A core electric wire for multi-core cable according to an aspect of the present invention comprises a conductor obtained by twisting element wires, and an insulating layer that covers an outer periphery of the conductor, in which, in a transverse cross section of the conductor, a percentage of an area occupied by void regions among the element wires is from 5% to 20%. An average area of the conductor in the transverse cross section is preferably from 1.0 mm.sup.2 to 3.0 mm.sup.2. An average diameter of the element wires in the conductor is preferably from 40 m to 100 m, and the number of the element wires is preferably from 196 to 2,450. The conductor is preferably obtained by twisting stranded element wires obtained by twisting subsets of element wires. The insulating layer preferably comprises as a principal component a copolymer of ethylene and an -olefin having a carbonyl group.

An electric wire for improving the adhesion force between the adjacent winding wires of a coil is described. The electric wire of the present invention may include a conductive wire with a substantially quadrilateral cross-sectional shape. The electric wire further includes a first groove and a second groove positioned diagonally at two opposite corners of the quadrilateral along a longitudinal direction of the conductive wire. An adhesive pocket filled with an adhesive is sized to fit within each of the first and second grooves at diagonally arranged opposite corners.

An electric wire for improving the adhesion force between the adjacent winding wires of a coil is described. The electric wire of the present invention may include a conductive wire with a substantially quadrilateral cross-sectional shape. The electric wire further includes a first groove and a second groove positioned diagonally at two opposite corners of the quadrilateral along a longitudinal direction of the conductive wire. An adhesive pocket filled with an adhesive is sized to fit within each of the first and second grooves at diagonally arranged opposite corners.

A high frequency signal transmission cable includes a conductor, an insulator provided over a periphery of the conductor, a plating layer provided over a periphery of the insulator, and a sheath provided over a periphery of the plating layer. A crack suppressing layer includes a non-cross-linked polyethylene is provided between the insulator and the plating layer, in such a manner as to remain in contact with the insulator while being provided with the plating layer over an entire periphery of a roughened outer surface of the crack suppressing layer. The crack suppressing layer is unadhered to the insulator. The plating layer is adhered to the crack suppressing layer. The crack suppressing layer suppresses an occurrence of a cracking in the plating layer by bending together with the plating layer while being integral and moving with the plating layer in a longitudinal direction of the cable.

A high frequency signal transmission cable includes a conductor, an insulator provided over a periphery of the conductor, a plating layer provided over a periphery of the insulator, and a sheath provided over a periphery of the plating layer. A crack suppressing layer is provided between the insulator and the plating layer, in such a manner as to remain in contact with the insulator while being provided with the plating layer over an outer surface of the crack suppressing layer. The crack suppressing layer suppresses the occurrence of a cracking in the plating layer by bending while moving in a longitudinal direction of the cable relative to a bending of the insulator.

A high frequency signal transmission cable includes a conductor, an insulator provided over a periphery of the conductor, a plating layer provided over a periphery of the insulator, and a sheath provided over a periphery of the plating layer. A crack suppressing layer is provided between the insulator and the plating layer, in such a manner as to remain in contact with the insulator while being provided with the plating layer over an outer surface of the crack suppressing layer. The crack suppressing layer suppresses the occurrence of a cracking in the plating layer by bending while moving in a longitudinal direction of the cable relative to a bending of the insulator.

An electric wire for improving the adhesion force between the adjacent winding wires of a coil is described. The electric wire of the present invention may include a conductive wire with a substantially quadrilateral cross-sectional shape. The electric wire further includes a first groove and a second groove positioned diagonally at two opposite corners of the quadrilateral along a longitudinal direction of the conductive wire. An insulator pocket filled with an insulator is sized to fit within each of the first and second grooves at diagonally arranged opposite corners.

A method for reducing frequency dependent energy loss and phase errors from end to end as a function of the frequency of audio-range signals conducted therein including obtaining an electrical wire having a first end and an opposing second end and comprising of an electrically conductive metal with a conductivity between 0 and about 3.2* 10.sup.6 (ohm-meter).sup.1 or between 0 and about 5.5% International Annealed Copper Standard (IACS), wherein the electrically conductive metal includes a relative magnetic permeability between 0 and 2, and transmitting audio-range signals from the first end to the second end, wherein the frequency dependent energy loss and phase from the first end to the second end is a function of a frequency of the audio-range signals transmitted therein.

A method for reducing frequency dependent energy loss and phase errors from end to end as a function of the frequency of audio-range signals conducted therein including obtaining an electrical wire having a first end and an opposing second end and comprising of an electrically conductive metal with a conductivity between 0 and about 3.2* 10.sup.6 (ohm-meter).sup.1 or between 0 and about 5.5% International Annealed Copper Standard (IACS), wherein the electrically conductive metal includes a relative magnetic permeability between 0 and 2, and transmitting audio-range signals from the first end to the second end, wherein the frequency dependent energy loss and phase from the first end to the second end is a function of a frequency of the audio-range signals transmitted therein.