LOW ATTENUATION FLAT FLEXIBLE CABLE

• US 3,818,117 A
• Filed: 04/23/1973
• Issued: 06/18/1974
• Est. Priority Date: 04/23/1973
• Status: Expired due to Term

• Current Assignee: Emerson Marshall Ii Reyner, Jerry Hench Bogar
• Original Assignee: Emerson Marshall Ii Reyner, Jerry Hench Bogar
• Inventors: Bogar, Jerry Hench, Reyner, Emerson Marshall II
• Primary Examiner(s): Gilheany, Bernard A.
• Assistant Examiner(s): Grimley, A. T.
• Application Number:
  US05/353,257
• Time in Patent Office: 421 Days
• Field of Search: 333/84M,84R,32,72S,81A 174/36,117F,117FF,78,117PC,88C
• US Class Current: 174/36
• CPC Class Codes: H01B 11/00 Communication cables or conductors
• CPC Class Codes: H01B 7/0838 Parallel wires, sandwiched between two insulating layers
• CPC Class Codes: H05K 1/0224 Patterned shielding planes, ground planes or power planes H05K1/0253 takes precedence
• CPC Class Codes: H05K 1/0253 Impedance adaptations of transmission lines by special lay-out of power planes, e.g. providing openings H05K1/0251 takes precedence
• CPC Class Codes: H05K 1/0393 Flexible materials H05K1/038 takes precedence; specific organic compositions are classified in H05K1/0313 and subgroups
• CPC Class Codes: H05K 2201/0715 provided by an outer layer of PCB
• CPC Class Codes: H05K 2201/09663 Divided layout, i.e. conductors divided in two or more parts branched layout H05K2201/09254
• CPC Class Codes: H05K 2201/09681 Mesh conductors, e.g. as a ground plane

Abstract

A flat shielded cable comprising a plurality of parallel spacedapart signal conductors in a first plane and a shield member in the form of a conductive ground plane facing the signal conductors and being positioned in a second plane, the shield member having preselected amounts of conductive material removed in the area opposite the signal conductors to form ground lines, which are parallel to the signal conductors to control the characteristic impedance of the cable, and also to form parallel, conductive shunting paths between the ground lines at predetermined intervals to correct for excessive attenuation caused by skewing of the signal conductors with respect to the ground lines.

Claims

1. A flat cable for transmitting signals comprising:

a plurality of transmission lines formed by a plurality of flat parallel spaced-apart signal conductors lying in a single plane and associated corresponding pairs of a plurality of parallel flat shield conductors lying in a plane parallel to the single plane of said signal conductors, said shield conductors extending parallel to said signal conductors and being laterally offset from said signal conductors, a plurality of parallel shunt conductors interconnecting said shield conductors at spaced intervals, and insulating material between said conductors and encasing said conductors, said shunt conductors preventing signal coupling between any indiVidual transmission line and another transmission line formed by the pair of shield conductors associated with the individual transmission line.

2. A flat cable as recited in claim 1 wherein said shunt conductors are arranged substantially perpendicularly to said shield conductors.

3. A flat cable as recited in claim 2 wherein said shunt conductors and said shield conductors are formed from a single substantially continuous layer of conductive material.

4. A flat cable as recited in claim 2 wherein the spacing between said shunt conductors is selected to be a fraction of the wavelength of the signals to be transmitted by said cable.

5. A cable as recited in claim 4 wherein the spacing between said shunt conductors is selected to be substantially equal to L where:

L upsilon /4f and upsilon the speed of electromagnetic wave propragation in said cable and f the frequency of the signals to be transmitted by said cable.

6. A cable as recited in claim 4 wherein the spacing between said shunt conductors is selected to be substantially less than L'"'"''"'"' where:

L'"'"''"'"' upsilon /2f and upsilon the speed of electromagnetic wave propagation in said cable and f the highest frequency of the signals transmitted by said cable.

7. A cable as recited in claim 2 wherein the ratio of the width of each said shunt conductors to the center-to-center spacing between adjacent shunt conductors in a direction parallel to said shield conductors is less than or equal to one tenth.

8. A terminated flat cable comprising:

a plurality of parallel spaced-apart signal conductors lying in a single plane, a plurality of flat electrically conductive shielding means lying in a plane extending parallel to, and spaced from, said single plane, dielectric material between said signal conductors and said shielding means, a transversely extending zone adjacent to one end of said cable which is devoid of said conductive shielding means, and flat electrically conductive shunt means lying in said plane of said plurality of shielding means and interconnecting said plurality of shielding means at spaced intervals and being oriented in a direction substantially perpendicular to said parallel signal conductors.

9. A cable as recited in claim 2 wherein the spacing between shunt conductors is varied along the length of cable.

10. The structure as recited in claim 1, wherein said shield conductors are electrically ground.

11. A transmission cable comprising:

at least one elongated signal conductor, an associated pair of shield conductors elongated and parallel to the signal conductor, providing a transmission line and a plurality of spaced shunt conducting paths joining the shield conductors at intervals along their lengths to prevent signal coupling between said transmission line and another transmission line formed by the two shield conductors.