Communications connectors including transmission lines having impedance discontinuities that improve return loss and/or insertion loss performance and related methods
Communications plugs are provided that include a housing that receives the conductors of the communication cable. A printed circuit board is mounted at least partially within the housing. A plurality of plug contacts are on the printed circuit board, and the printed circuit board includes a plurality of conductive paths that electrically connect respective ones of the conductors to respective ones of the plug contacts. First and second of the conductive paths are arranged as a first differential pair of conductive paths that comprise a portion of a first differential transmission line through the communications plug, where the first differential transmission line includes a first transition region where the impedance of the first differential transmission line changes by at least 20% and a second transition region impedance of the first differential transmission line changes by at least 20%.
1. A patch cord comprising:
a communications cable that includes at least a first conductor, a second conductor, a third conductor and a fourth conductor; and
a plug that is attached to a first end of the communications cable, the plug comprising:
a housing that receives the communications cable;
a first plug contact, a second plug contact, a third plug contact and a fourth plug contact that each are at least partially within the housing;
a first conductive path that connects the first conductor to the first plug contact, a second conductive path that connects the second conductor to the second plug contact, a third conductive path that connects the third conductor to the third plug contact, and a fourth conductive path that connects the fourth conductor to the fourth plug contact,
wherein the first and second conductors, the first and second conductive paths, and the first and second plug contacts form a first differential transmission line through the plug and the third and fourth conductors, the third and fourth conductive paths, and the third and fourth plug contacts form a second differential transmission line through the plug, and
wherein the first differential transmission line includes at least a first segment having a first impedance, a second segment having a second impedance, and a third segment having a third impedance, wherein the second segment is between the first and third segments, and wherein the first impedance is different than the second impedance and the second impedance is different than the third impedance, and
wherein the first, second and third impedances and/or the electrical lengths of the first, second and third sections are selected to provide a local maximum in the return loss spectra of the first differential transmission line.
2. The patch cord of claim 1 , wherein the first through fourth conductive paths each traverse a printed circuit board, and wherein the first segment of the first differential transmission line connects to the second segment of the first differential transmission line on the printed circuit board.
3. The patch cord of claim 2 , wherein the plug comprises an RJ-45 plug.
4. The patch cord of claim 3 , wherein the first plug contact is directly adjacent to the second plug contact.
5. The patch cord of claim 2 , wherein the second segment of the first differential transmission line connects to the third segment of the first differential transmission line on the printed circuit board.
6. The patch cord of claim 2 , wherein a first pair of conductive trace sections on the printed circuit board that form the first segment of the first differential transmission line have widths and/or thicknesses and/or distances from adjacent image plane(s) and/or effective dielectric constants that are different than the corresponding widths and/or thicknesses and/or image plane distance(s) and/or effective dielectric constants of a second pair of conductive trace sections on the printed circuit board that form the second segment of the first differential transmission line.
7. The patch cord of claim 2 , wherein the impedance of the first segment of the first differential transmission line differs from the impedance of the second segment of the first differential transmission line by at least 20 percent, and wherein the impedance of the second segment of the first differential transmission line differs from the impedance of the third segment of the first differential transmission line by at least 20 percent.
8. The patch cord of claim 2 , wherein the local maximum in the return loss spectra of the first differential transmission line is between a frequency of 1 GHz and a frequency of 5 GHz.
9. The patch cord of claim 1 , wherein the local maximum in the return loss spectra of the first differential transmission line is positioned within the return loss spectra in order to extend the operating frequency range of the patch cord over which a minimum return loss margin may be maintained.
10. The patch cord of claim 1 , wherein the local maximum in the return loss spectra of the first differential transmission line is within a pre-selected frequency range of an operating frequency range of the patch cord.
11. The patch cord of claim 1 , wherein the local maximum in the return loss spectra of the first differential transmission line is at a frequency that is outside the operating frequency range of the patch cord.
12. The patch cord of claim 1 , wherein the second differential transmission line includes at least a fourth segment having a fourth impedance, a fifth segment having a fifth impedance, and a sixth segment having a sixth impedance, wherein the fifth segment is between the fourth and sixth segments, wherein the fourth impedance is different than the fifth impedance and the fifth impedance is different than the sixth impedance, and wherein the fourth, fifth and sixth impedances are selected to provide a local maximum in the return loss performance of the second differential transmission line within the pre-selected frequency range.