×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Does VSWR affect Crosstalk?
3

Does VSWR affect Crosstalk?

Does VSWR affect Crosstalk?

(OP)
As I understand it, VSWR is a measure of how much of a signal gets reflected back to the source in a transmission line, and crosstalk is a measure of how much coupling exists between channels in a transmission line system.

Is there a relationship between VSWR and crosstalk?

For example, I have identified two points of impednace mis-match in a 'transmission line' using TDR (time domain reflectometry). I assume that these two points of mismatch will make the VSWR worse. Does it also follow that the crosstalk will be worse due to these two points?

Thank you for your help!

Best regards,

BPELEC.
 

RE: Does VSWR affect Crosstalk?

There is no general relationship between cross-talk and VSWR.

As you have pointed out, VSWR is a measure of mismatch at an input. (VSWR can be calculated from the reflection coefficient).

Cross-talk is a measure of coupling between two apparently unconnected but nearby systems. The two effects may be coupled on any particular system, but there is no general connection. Mis-match need not be due to adjacent channel coupling.

RE: Does VSWR affect Crosstalk?

Logbook is correct, and to state it the other way, there is no general relationship between VSWR and crosstalk.  

An impedance mismatch will give a reflection that will put higher voltages at some points along the transmission line and higher currents at other points along the t-line.  Crosstalk is due to coupling - capacitive coupling of the voltage, or inductive coupling of the current.  If your reflection happens to cause a V or I increase at a point where the coupling is high you will get more crosstalk.  So while you are correct that high VSWR can effect your crosstalk, it isn't a linear effect; it might get much worse or there may be negligible change.  

Your crosstalk could be a partial cause of the VSWR too; if you have a lot of coupling to adajacent lines your characteristic impedance may not be what you designed for.  

RE: Does VSWR affect Crosstalk?

There is not general relationship between the two. However, in a coaxial system feeding into a non-coaxial, a mismatch may cause the reflected energy to flow back down the outside of the coax. This reflection down the shield of the coax may then be coupled into adjacent wires or cables. Such situations usually happen at the feed point of antennas, and a choke on the outside of the coax may be used to reduce effect.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources