Open circuited quarter wave transmission line

Click For Summary
SUMMARY

The discussion focuses on analyzing an open-circuited quarter wave transmission line, emphasizing the importance of calculating the impedance at the open end rather than assuming it to be infinite. Participants highlight that a mismatched quarter wave transmission line functions as a transformer, necessitating the calculation of the impedance ratio to the generator's 50 ohms. The voltage ratio can then be derived from this impedance ratio. The use of ABCD parameters is suggested for handling complex mismatches, such as a 300-ohm transmission line connected to a 50-ohm source.

PREREQUISITES
  • Understanding of quarter wave transmission line theory
  • Knowledge of impedance transformation principles
  • Familiarity with ABCD parameters in transmission line analysis
  • Basic concepts of voltage and impedance ratios
NEXT STEPS
  • Study the calculation of impedance at open-circuited transmission lines
  • Learn about the application of ABCD parameters in transmission line theory
  • Research the principles of voltage and impedance ratios in transformers
  • Explore mismatched transmission line scenarios and their solutions
USEFUL FOR

Electrical engineers, telecommunications professionals, and students studying transmission line theory and impedance matching techniques.

reddvoid
Messages
118
Reaction score
1

Homework Statement



attachment.php?attachmentid=54441&stc=1&d=1357318145.jpg


The Attempt at a Solution


I m getting 10V as one side is O.C so the whole voltage come across it...correct me where i m going wrong
 

Attachments

  • 386638_4966527478180_2132481737_n.jpg
    386638_4966527478180_2132481737_n.jpg
    29 KB · Views: 669
Physics news on Phys.org
You're going about it wrong. First calculate the impedance at the open end of the transmission line. Hint, it's not infinite. A mismatched 1/4 wave transmission line acts like a transformer. After you calculate the impedance at the open end, then calculate the ratio of that impedance to the 50 ohms of the generator. Lastly, how does the ratio of voltages compare to the ratio of impedances of a transformer? If you first find the ratio of impedances then from that you can find the ratio of voltages. Once you've done that you would just multiply the input voltage by the voltage ratio.
 
I would use ABCD parameters, concatenating the ABCD parameters for the 50 ohm source resistor with the abcd parameters for the xmsn line. This method can handle any kind of oddball mismatches, such as in this case the 300 ohm xmsn line to the 50 ohm source, and any desired length of line (here λ/4) and far-end termination impedance (here ∞).

I'm sure that's overkill here & that there's an esier way, as skeptic2 is suggesting. Just pointing out that abcd parameters can handle the most general cases.
 
got it :)
attachment.php?attachmentid=54473&stc=1&d=1357392250.jpg
 

Attachments

  • n.jpg
    n.jpg
    46.9 KB · Views: 663
Your handwriting is cool. :biggrin:
 

Similar threads

  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 18 ·
Replies
18
Views
3K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K
Replies
5
Views
2K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 24 ·
Replies
24
Views
8K
  • · Replies 15 ·
Replies
15
Views
2K