# Talk:Primary line constants

I would like to propose splitting and merging this article with "Telegrapher's Equations" or "Propagation constant". This article has good information that should be available in those articles.  There is information here regarding the Telegrapher's Equations that does not appear in "Telegrapher's Equations".   The primary line constants have physical meaning and exist even if the Telegrapher's Equations did not exist, so this topic should exist.  I think everything from the "Characteristic impedance" section on should be merged with "Telegrapher's Equations" or "propagation constant".   And if it is too much detail for those articles, then perhaps the detailed part should go into a new article called something like "Telegrapher's Equations -- Detailed Derivation" and a link provided to it in the "Telegrapher's Equations" article. Constant314 (talk) 16:24, 31 May 2010 (UTC)

Overlap is not in itself a bad thing.  It is often necessary so that each article can stand on its own.  SpinningSpark 16:56, 31 May 2010 (UTC)

I suspect that at high frequency that the secondary constants are measured and the primary constants are calculated from that.
At low frequencies I suspect that it is measured just like any R, L C, or G component. Constant314 (talk) 03:11, 29 October 2012 (UTC)

R, C and G are easily measured directly.  L is usually more difficult as in most cables it is swamped by the others, especially C, so is more often calculated. Cables with modern dielectric material, especially when new, have G so low that a substantial length of cable is needed to measure accurately. SpinningSpark 07:17, 29 October 2012 (UTC)
I must admit that I don't know how anybody else measures the primary parameters, but the last time I needed to do that in the 1 MHz+ range I used an impedance/network analyzer that gave me the secondary parameters and then used them to calculate the primary parameters.  I probably did it that way because of the available instrumentation.Constant314 (talk) 23:20, 29 October 2012 (UTC)

This review is transcluded from Talk:Primary line constants/GA1. The edit link for this section can be used to add comments to the review.
Reviewer: Reaper Eternal (talk · contribs) 10:31, 7 August 2013 (UTC)
Hi! I'm currently working on reviewing this article. I should be back in a couple of days or less with my review. Good luck! Reaper Eternal (talk) 10:31, 7 August 2013 (UTC)

Thanks for reviewing Reaper.  I look forward to seeing your review.  SpinningSpark 11:48, 7 August 2013 (UTC)
Lead
"The primary line constants are parameters that describe the characteristics of copper or other conductive material transmission lines in terms of the physical electrical properties of the line." – Since this article is about the constants describing transmission lines rather than the transmission lines themselves, I don't think the red part is necessary. It's awkwardly positioned and really doesn't add anything, since all electrical transmission lines use copper or other conductive materials. The phrase could probably also be replaced with just "electrical", which would concisely describe what type of transmission lines are being discussed.
The constants
Am I correct in assuming that the table is sourced to references [1] and [2]?
Measurement of primary line constants
This section is completely empty!
Typical values for some common cables
This table could probably benefit from an introductory sentence or two.
What do blank table cells mean, that the value is negligible?
Circuit representation
In the circuits, you show the small element variables like 
  
    
      
        δ
        L
      
    
    {\displaystyle \delta L}
  
. However, in the calculations, you refer to the infinitesimal elements like 
  
    
      
        d
        L
      
    
    {\displaystyle dL}
  
. I don't really know if it is necessary to explain how you got from small to infinitesimal, since it is likely that the only people who will read this section are familiar with basic calculus. However, it might be nice to include a sentence like: "To give a true representation of the circuit, the elements must be made infinitesimally small so that each element is distributed along the line as shown in figure 1. Thus, 
  
    
      
        δ
        L
        →
        d
        L
      
    
    {\displaystyle \delta L\rightarrow dL}
  
, 
  
    
      
        δ
        C
        →
        d
        C
      
    
    {\displaystyle \delta C\rightarrow dC}
  
, and 
  
    
      
        δ
        R
        →
        d
        R
      
    
    {\displaystyle \delta R\rightarrow dR}
  
. The infinitesimal elements in an infinitesimal distance 
  
    
      
        d
        x
      
    
    {\displaystyle dx}
  
 are given by...." Feel free to take or leave this suggestion.
The clause, "...the elements must be made infinitesimally small so that each element is distributed along the line as shown in figure 1", is confusing since it implies the variables 
  
    
      
        δ
        L
      
    
    {\displaystyle \delta L}
  
 and others are infinitesimals.
Characteristic impedance
This section looks good.
Propagation constant
The first sentence makes it sound like 
  
    
      
        δ
        x
      
    
    {\displaystyle \delta x}
  
 is an infinitesimal. I thought 
  
    
      
        d
        x
      
    
    {\displaystyle dx}
  
 was the infinitesimal. Is this what you meant?
Special cases
This section looks good.
Notes
You have almost no metadata for your web references.
References
All sources are reliable, which is excellent.
Why is title capitalization not being used for the latter three titles?
Overall
This is a good technical article that mostly covers the topic. Apart from the one empty section, I don't see any significant omissions. Some reference formatting and clarification issues remain, but I don't see why this shouldn't pass GAN after these issues are fixed. Thanks for your hard work! Reaper Eternal (talk) 13:25, 7 August 2013 (UTC)


### Responses from Spinningspark
copper lines
Not looked at the history, but the cack-handed wording probably arose because I wrote "copper lines" (a common enough shorthand in telecommunications, and mostly accurate since lines are invariablly made of copper) and someone else followed on trying to make it more precise.  I don't think we can just say "transmission lines" since many sources will include waveguides in the class of transmission line.  There are also dielectric waveguides which include no metal at all.  Can we agree on "...of conductive trasmission lines, such as pairs of copper wires, in terms..." SpinningSpark 15:08, 7 August 2013 (UTC)

That seems reasonable. Reaper Eternal (talk) 15:37, 7 August 2013 (UTC)
Done. SpinningSpark 17:54, 7 August 2013 (UTC)
Table
The table is merely a list of the constants.  Nothing controversial there.  What is the problem? SpinningSpark 15:08, 7 August 2013 (UTC)

I'm referring to the table under "Typical values for some common cables". Specifically, there is no introductory text to describe what the table is and why it is there. Additionally, adding introductory text will allow you to move footnote #5, which isn't a reference, into the main text. Reaper Eternal (talk) 12:42, 15 August 2013 (UTC)
Sorry for the confusion, I was responding to your comment on the table in "The constants" section.  I have removed #5 from the endnotes and made it a footnote to the table.  I don't really know what introductory text could be added that has not been said in the previous section.  It is a table of typical values of some common tables.  The heading says it all already. SpinningSpark 21:41, 15 August 2013 (UTC)
Circuit representation
I don't think it needs to be made explicit that the limit of δL is dL etc.  Basic maths and the article already says something equivalent.  However, I have added that δL=Lδx etc.  I have moved the ref to figure 1 to clarify. SpinningSpark 15:08, 7 August 2013 (UTC)

Okay. Thanks. Reaper Eternal (talk) 12:42, 15 August 2013 (UTC)
Propagation constant
Yes, you are right.  Deleted "inifinitesimal". SpinningSpark 15:24, 7 August 2013 (UTC)

Thanks. Reaper Eternal (talk) 12:42, 15 August 2013 (UTC)
Empty section
This was added by Constant314.  There is some discussion on the talk page.  I know perfectly well how to make these measurements as I have done it regularly as part of my professional duties.  The problem is the lack of sources.  The alternatives we have, unless you can point to a source, are to delete the section or write something unsourced. SpinningSpark 15:24, 7 August 2013 (UTC)

Would this source work? Myeong-ryeal, Jeon; Sei-ill, Oh; Hee, Lee; Chang-gyun, Shin (Winter 2008). "Analysis of Measured Transmission Line Constants" (PDF). South Korea: Electric Power Research Institute. pp. 36–39. Retrieved 7 August 2013. Reaper Eternal (talk) 15:37, 7 August 2013 (UTC)
Unfortunately not.  The linked article is about power distribution and the "constants" they are talking about are what we would call source impedance in telecomms.  They are talking about the properties of primary lines (primary-line constants) whereas we are talking about the primary constants of lines (primary line-constants). SpinningSpark 17:47, 7 August 2013 (UTC)
Okay. I didn't know if the principles still applied. Removing the empty section is a good idea then. Reaper Eternal (talk) 12:28, 15 August 2013 (UTC)
References
Capitalization fixed. SpinningSpark 15:56, 7 August 2013 (UTC)

Thanks. Reaper Eternal (talk) 12:28, 15 August 2013 (UTC)
Notes
The links are mostly to data sheets which often do not have much in the way of metadata to cite.  What were you looking for? SpinningSpark 15:56, 7 August 2013 (UTC)

I was looking for what you added in your latest edit. ;) Reaper Eternal (talk) 12:28, 15 August 2013 (UTC)
Figures
Are you sure that capitalising Figure is consistent with MOS:CAP? SpinningSpark 09:37, 8 August 2013 (UTC)

(Pardon the interruption; I was browsing the Engineering GA noms and saw this) - I was wondering this when I reviewed your other nomination.  It seems to me that capitalising Figure in-line would be appropriate because in some way you are referring to a figure by its title, "Figure X".  But I wasn't sure then and I'm not sure now.  MOS:CAP doesn't appear to have anything definite either way, but if someone finds something definitive one way or another I'd like to know. Corvus coronoides talk 03:05, 9 August 2013 (UTC)
The opening sentence of the MOS is Wikipedia avoids unnecessary capitalization.  Seems to me that is making the pretty definite statement that the default is not to capitalise for situations that do not explicitly mandate caps.  I have several articles that have reached FA (Mechanical filter, Distributed element filter) which use lowercase for figure and the review of at least one of them explicitly discussed this very issue.  The Chicago Manual of Style calls for lowercase references to chapter numbers[1] which I would maintain is a comparable situation.  In fact, thinking about it, figures are even lower down the hierarchy than chapters since the former are contained within the latter. SpinningSpark 10:56, 9 August 2013 (UTC)
Ehh, I guess lowercase is fine, although every single citation system that I know of uses uppercase "Figure ##" and "Table ##" cross-referencing. Reaper Eternal (talk) 12:24, 15 August 2013 (UTC)
I appear to have started this thread on the wrong article.  Apologies for the mistake, Antimetric electrical network was the article in question, not this one.  Pinging User:Corvus coronoides.  In response to your comment, citations are not running text which is what Chicago is talking about. SpinningSpark 21:41, 15 August 2013 (UTC)
Velocity
In looking at the table question above I realised the article could do with a section on velocity to explain the effect of C on velocity, especially for low-loss cable.  Sorry for giving you something more to review. SpinningSpark 21:41, 15 August 2013 (UTC)

That's fine! I don't mind reviewing additional content if gaps in the article's coverage are discovered. I've given everything a final review, and I believe this article meets everything required in WP:WIAGA. The prose is of good quality, there are no real gaps in knowledge save the one explained above, sourcing is good, and the images are being used in accordance with copyright. There are no edit wars or biases present. Thus, I am passing this article. Thank you for your contributions! Reaper Eternal (talk) 12:29, 21 August 2013 (UTC)
Thanks very much for your efforts in reviewing this article.  I will keep a look out for sources on measurement techniques, but there really doesn't seem to be much out there. SpinningSpark 13:30, 21 August 2013 (UTC)