High density shielded electrical cable and other shielded cables, systems, and methods

A shielded electrical ribbon cable, comprising:

• a plurality of conductor sets extending lengthwise along the cable and arranged generally in a plane along a width of the cable, at least 90% of a periphery of each conductor set surrounded by and fixably coupled to an electrically conductive shield each conductor set including two insulated conductors;
• and
• first and second non-conductive polymeric layers disposed on opposite sides of the cable, the first and second polymeric layers including cover portions and pinched portions arranged such that, in transverse cross section, the cover portions of the first and second polymeric layers in combination substantially surround the plurality of conductor sets, and the pinched portions of the first and second polymeric layers in combination form pinched portions of the cable on each side of the cable, the cable comprising a transition portion on each side of the cable defined by the first and second polymeric layers and end conductors of the conductor sets nearest the pinched portions, the transition portions providing gradual transitions between the cover portions and the pinched portions of the first and second polymeric layers such that when the cable is laid flat:
• at least one of the first and second polymeric layers has a radius of curvature of at least 50 microns across an entire width of the cable;
• and
• for the at least one of the first and second polymeric layers, a ratio of a minimum radius of curvature in the cover portions to a minimum radius of curvature in the transition portions is in a range from 2 to 15, wherein the plurality of conductor sets comprises adjacent first and second conductor sets, the first conductor set having a high frequency isolation between the two insulated conductors characterized by a crosstalk C1 at a specified frequency in a range from 3 to 15 GHz and for a 1 meter cable length, wherein a high frequency isolation between the first and second conductor sets is characterized by a crosstalk C2 at the specified frequency, and wherein C2 is at least 10 dB lower than C1.