Lossy Drain Wire on a High Speed Cable
A dual axial cable includes first and second signal conductors, a shield, and a drain wire. The first and second signal conductors transmit a differential signal. The shield is spirally wrapped around the first and second conductors, and causes a resonant characteristic of the dual axial cable. The drain wire provides a return path for the differential signal in the dual axial cable. The drain wire is roughened to a specific amount of roughness, which reduces signal loss at resonant frequencies of the resonant characteristic caused by the shield.
1 . A dual axial cable comprising:
first and second signal conductors to transmit a differential signal;
a shield spirally wrapped around the first and second conductors, wherein the shield causes a resonant characteristic of the dual axial cable; and
a drain wire to provide a return path for the differential signal, the drain wire being roughened to a specific amount of roughness, wherein the specific amount of roughness causes a reduction of a signal loss at resonant frequencies of the resonant characteristic caused by the shield.
2 . The dual axial cable of claim 1 , further comprising:
a first insulator surrounding the first conductor and in physical communication with the shield.
3 . The dual axial cable of claim 2 , further comprising:
a second insulator surrounding the second conductor and in physical communication with the shield.
4 . The dual axial cable of claim 1 , wherein the specific amount of roughness is within a range of roughness from 25 μm to 250 μm.
5 . The dual axial cable of claim 1 , wherein the spiral wrapping of the shield causes overlaps in the shield.
6 . The dual axial cable of claim 5 , wherein the resonant frequencies are caused by the overlap in the shield.
7 . The dual axial cable of claim 1 , wherein the reduction of the signal loss at the resonant frequencies is independent from frequencies that the dual axial cable is operated.
8 . A dual axial cable comprising:
first and second signal conductors to transmit a differential signal;
a shield spirally wrapped around the first and second conductors, wherein the shield causes a resonant characteristic of the dual axial cable;
a first drain wire to provide a first return path for the differential signal; and
a second drain wire to provide a second return path for the differential signal, the first and second drain wires being roughened to a specific amount of roughness, wherein the specific amount of roughness causes a reduction of a signal loss at resonant frequencies of the resonant characteristic caused by the shield.
9 . The dual axial cable of claim 8 , further comprising:
a first insulator surrounding the first conductor and in physical communication with the shield.
10 . The dual axial cable of claim 9 , further comprising:
a second insulator surrounding the second conductor and in physical communication with the shield.
11 . The dual axial cable of claim 8 , wherein the specific amount of roughness is within a range of roughness from 25 μm to 250 μm.
12 . The dual axial cable of claim 8 , wherein the spiral wrapping of the shield causes overlaps in the shield.
13 . The dual axial cable of claim 12 , wherein the resonant frequencies are caused by the overlap in the shield.
14 . The dual axial cable of claim 8 , wherein the reduction of the signal loss at the resonant frequencies is independent from frequencies that the dual axial cable is operated.
15 . A method comprising:
determining a desired dampening of signal loss at resonant frequencies of a dual axial cable;
roughening a drain wire in the dual axial cable to a roughness derived based on the desired dampening of the signal loss at the resonant frequencies; and
spirally wrapping the drain wire and first and second conductors with a shield, wherein spirally wrapping of the shield high cause signal loss at resonant frequencies unless dampened by a roughened drain wire.
16 . The method of claim 15 , further comprising:
surrounding the first conductor by a first insulator prior to spirally wrapping the drain wire and the first and second conductors with the shield; and
surrounding the second conductor by a second insulator prior to spirally wrapping the drain wire and the first and second conductors with the shield.
17 . The method of claim 15 , wherein the dampening of the signal loss at the resonant frequencies is independent from frequencies that the dual axial cable is operated.
18 . The method of claim 15 , wherein the derived roughness is within a range of roughness from 25 μm to 250 μm.
19 . The method of claim 15 , wherein the spiral wrapping of the shield causes overlaps in the shield.
20 . The method of claim 19 , wherein the resonant frequencies are caused by the overlap in the shield.