So to start from the top you’ve got an impedance that’s both the wrong magnitude and also wrong phase. So what you’re able to do is cancel out the undesirable (reactive) component of the transmission line-transformed impedance that you already had. You’re adding a purely imaginary impedance (a reactive impedance). So you’re definitely not changing the real magnitude of the signal (I’m assuming you’re adding these stubs on the source end, right?). So you can change the magnitude of the current that’s in phase with the source voltage by changing the reflection time delay, and so change the real component of the impedance.Ģ: all open or shorted transmission line segments are lossless, right? So they will always have zero real impedance because real impedance = net power transfer = loss. And when current and voltage are in phase that’s a real impedance. But the reason that this is worthwhile is that the component of the load’s current that projects onto the source voltage can be changed this way. Yes, you’re changing the phase of the reflected load. Second 1: so you’re basically changing the real magnitude by doing this. The effect of adding a transmission line is always just a phase delay, so you’re just seeing the (constant magnitude) reflected signal change phase. Why do we move clockwise (wavelengths towards generator) when adding in transmission line? Why do we not use wavelengths towards load? I feel like that would make more sense if we are adding in linesġ: yes, absolutely. Why is 0.25 of the wavelength so important? Why is the input impedance seen on various points on the T-line so different (I think the magnitude and phase fluctuates)? Is this something to do with the reflected waves? Does this mean adding in the short/open stub corrects the magnitude of the reflection coefficient? When we add in the short/open stub, this brings the normalized impedance to the center of the smith chart. When we move clockwise down the constant reflection coefficient circle to the real 1, are we adding T-line length to correct the phase of the reflection coefficient? Since the magnitude of the reflection coefficient isn't changing However, adding that much T-line also changes the reactive parts of the impedance, and we had to add the appropriate length short/open stub to correct this. That is where we learned how much T-line length to add. Then, we traveled clockwise on that circle to the real 1. We started this by plotting the normalized load impedance/admittance, then drawing the constant reflection coefficient circle. We learned how to do impedance matching with a smith chart. Is this correct? So when we go around that constant reflection coefficient circle, is that just following the phase changes with T-line length changes (on the outer peripherals of the chart)? I have the following written down: magnitude of the reflection coefficient does not change with additional transmission line length added, but phase does change. When I'm using Smith Charts, I often have to draw constant reflection coefficient circles.We are focusing on lossless transmission lines right now. I don't know if I'm just overthinking things because I do have some fairly specific questions: I'm taking a RF Fields and Waves class right now and I just needed some help understanding some of the concepts in transmission line theory and how it relates to Smith Charts. Send the moderators a message and we can unblock it as soon as possible. If the problem is truly an engineering problem, we'll allow it, but fixing your laptop or a cracked LCD screen doesn't qualify.ĭo not post Discord links, surveys, or job postings (with the exception of the monthly job post).Ĭan't find your submission? It was probably caught by reddit's spam filters. Tech support help can be found in /r/gadgets. If you have specific, targeted questions regarding homework, we will help you out only if you have provided some beginning work. Power, electronics, electromagnetics, semiconductors, software engineering, embedded systems - all topics relevant to this field, professional or academic. Discuss anything related to the field of Electrical and Computer Engineering.
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