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 method of improving the return loss on a differential transmission line through a communications connector, wherein the communications connector is an 8 position 8 contact (8P8C) plug, the method comprising:
dividing the differential transmission line into at least a first segment, a second segment and a third segment, wherein a first impedance mismatch between the impedances of the first and second segments differs by at least 20%, and a second impedance mismatch between the impedances of the second and third segments differs by at least 20%;
selecting the first impedance mismatch and the second impedance mismatch to improve the return loss performance of the differential transmission line in a pre-selected frequency range; and
selecting a length of the first segment, a length of the second segment and a length of the third segment to improve the return loss performance of the differential transmission line in a pre-selected frequency range.
2. The method of claim 1 , wherein the communications connector is an 8 position 8 contact (8P8C) plug, and wherein the first segment of the differential transmission line comprises conductive traces on a printed circuit board and the third segment comprises a pair of plug contacts.
3. The method of claim 1 , wherein the first impedance mismatch is formed at least in part by implementing the first segment of the differential transmission line using conductive traces on a printed circuit board having first widths and/or a first spacing and by implementing the second segment of the differential transmission line using conductive traces on the printed circuit board having second widths and/or a second spacing that differ from the respective first widths or first spacing.
4. The method of claim 1 , wherein at least one of the first impedance mismatch or the second impedance mismatch is generated at least in part by a discrete reactance.
5. The method of claim 1 , wherein at least one of the first impedance mismatch or the second impedance mismatch is generated at least in part by providing a box-section filter along the differential transmission line.
6. The method of claim 1 , wherein a return loss spectra for the differential transmission line includes a local maxima in the upper half of the operating frequency range of the communications connector.
7. The method of claim 1 , wherein a return loss spectra for the differential transmission line includes a local maxima at a frequency that is above an operating frequency range of the communications connector.
8. A method of improving the return loss on a differential transmission line through a communications connector, the method comprising:
dividing the differential transmission line into at least a first segment, a second segment and a third segment, wherein a first impedance mismatch between the impedances of the first and second segments differs by at least 20%, and a second impedance mismatch between the impedances of the second and third segments differs by at least 20%,
wherein the communications connector is an 8 position 8 contact (8P8C) connector and the differential transmission line connects a pair of conductors of a communications cable to a pair of contacts of the 8 position 8 contact (8P8C) connector.
9. The method of claim 8 , wherein a return loss spectra for the differential transmission line includes a local maxima in the upper half of the operating frequency range of the communications connector.
10. The method of claim 8 , wherein a return loss spectra for the differential transmission line includes a local maxima at a frequency that is above an operating frequency range of the communications connector.
11. The method of claim 8 , wherein the communications connector is an 8 position 8 contact (8P8C) plug.
12. A method of improving the return loss on a transmission line through a communications connector, the method comprising:
including a plurality of impedance mismatches along the transmission line;
adjusting the magnitude of one or more of the impedance mismatches, the delay between one or more of the impedance mismatches and/or the number of impedance mismatches provided in order to reduce a rate of decrease in the return loss of the transmission line as a function of increasing frequency within a desired frequency operating range of the transmission line,
wherein rate of decrease in the return loss of the transmission line as a function of increasing frequency is reduced sufficiently such that a local maxima is generated in the return loss spectra that is at a frequency that is above the operating frequency range of the communications connector.
13. The method of claim 12 , wherein the transmission line comprises a differential transmission line through an 8 position 8 contact (8P8C) plug of a patch cord.