Trivial Smith Chart Question

[WolfOfTheSteps]

http://www.sss-mag.com/pdf/smithchart.pdf" , which scale at the bottom tells me the SWR?

Is it the top line or the second line? (Among the 4 straight lines at the bottom of the chart) I'm confused because on the right and left of the line there are two different labels (SWR and ATTEN). Also, is the units of SWR in dBS?

Thanks.

 

[abdo375]

The SWR is measured from the first line, yes you can measure the standing wave ratio in dBS but only if you want to (there is another scale, right??), only the right part of the first line is the SWR the left is ATTEN.

 

[piercas]

The scale at the bottom of the Smith Chart represents the Standing Wave Ratio (SWR) and is measured in terms of the reflection coefficient, with values ranging from 0 to infinity. The top line on the scale indicates the SWR values, while the second line indicates the corresponding Attenuation values. The units of SWR are not in dBS, as it is a ratio and does not have a unit of measurement. The Attenuation values on the second line are measured in decibels (dB). It is important to note that the Smith Chart is a graphical tool used for impedance matching and does not directly indicate SWR values. It can, however, be used to calculate the SWR by measuring the distance from the center of the chart to the plotted point and using the appropriate formula. I hope this clarifies any confusion you may have had about the scale at the bottom of the Smith Chart.

 

[piercas]

I am happy to clarify your confusion about the Smith Chart and its scales. The scale at the bottom of the chart that tells you the SWR (Standing Wave Ratio) is the top line. The second line is for attenuation. The units of SWR on the Smith Chart are not in dBS, but rather in a unitless ratio. The SWR is a measure of the mismatch between the input impedance and the characteristic impedance of a transmission line. It is typically represented as a ratio of the maximum voltage to the minimum voltage along the line. The higher the SWR, the greater the mismatch and the more energy is reflected back towards the source. The scale on the Smith Chart is designed to help visualize the relationship between the impedance and the SWR at different points along the transmission line. I hope this helps to clarify your question.