Shielded electrical cable

Abstract

A shielded electrical cable includes a conductor set that includes one or more substantially parallel longitudinal insulated conductors, a shielding film and two non-conductive polymeric layers disposed around the conductor set, The polymeric layers include concentric portions substantially concentric with at least one of the conductors having a first cross-sectional area and parallel portions where the polymeric layers are substantially parallel to each other. The cable further includes a transition portion providing a gradual transition between the concentric portions and the parallel portions of the polymeric layers, the transition portion having a second cross-sectional area defined as an area between the shielding film and the polymeric layers between first transition points where the polymeric layers deviate from being substantially concentric with the at least one of the conductors and second transition points where the polymeric layers deviate from being substantially parallel. The second cross-sectional area is equal to or smaller than the first cross-sectional area.

What is claimed is: 
     
         1 . A shielded electrical cable comprising:
 a conductor set including one or more substantially parallel longitudinal insulated conductors;   a shielding film disposed around the conductor set; and   two non-conductive polymeric layers disposed around the conductor set and including a concentric portion substantially concentric with at least one of the conductors having a first cross-sectional area and a parallel portion on at least one lateral side of the conductor set where the two non-conductive polymeric layers are substantially parallel to each other; and   a transition portion providing a gradual transition between the concentric portion and the parallel portion of the two non-conductive polymeric layers, the transition portion comprising a second cross-sectional area defined as an area between the shielding film and the two non-conductive polymeric layers between first transition points where the two non-conductive polymeric layers deviate from being substantially concentric with the at least one of the conductors and second transition points where the two non-conductive polymeric layers deviate from being substantially parallel, the second cross-sectional area being equal to or smaller than the first cross-sectional area.   
     
     
         2 . The shielded electrical cable of  claim 1 , wherein the second cross-sectional area is smaller than the first cross-sectional area. 
     
     
         3 . The shielded electrical cable of  claim 1 , wherein the second cross-sectional area is substantially the same along the length of the conductor. 
     
     
         4 . The shielded electrical cable of  claim 1 , wherein the shielded electrical cable includes transition portions positioned on each side of the conductor set. 
     
     
         5 . The shielded electrical cable of  claim 1  further comprising an adhesive layer disposed between the two non-conductive polymeric layers and bonding the two non-conductive polymeric layers to each other on at least one side of the conductor set. 
     
     
         6 . The shielded electrical cable of  claim 1 , wherein the insulated conductor has an insulation thickness, and wherein the transition portion has a lateral length defined as a length between the first transition points, wherein the lateral length is less than the insulation thickness. 
     
     
         7 . The shielded electrical cable of  claim 1 , wherein the transition portion has a lateral length defined as a length between the first transition points, wherein the lateral length is less than a diameter of the conductor. 
     
     
         8 . The shielded electrical cable of  claim 1  comprising a characteristic impedance that is within 5 to 10% of a target impedance value over a length of 1 meter.