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Smitih Charts, still relevant in 2024?

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pdenisowski:

--- Quote from: W4PJB on June 18, 2024, 04:44:20 pm ---Of course, it's also possible he was simply downplaying the fact that his unit didn't have one, so I would still buy it (I didn't).

--- End quote ---

It's very hard for me to imagine a VNA that doesn't have a Smith Chart display.  R&S is credited with manufacturing the first commercial network analyzer (the Z-g Diagraph) over 60 years ago and even that instrument had a Smith Chart display :)

Georgy.Moshkin:
Hey, tautech, I think you've got me wrong. I see polar and Cartesian plots on your images.. And what I was saying is that polar plot = Smith chart. And it's probably how it's implemented on most of VNAs firmware.

joeqsmith:

--- Quote from: Georgy.Moshkin on June 19, 2024, 09:45:41 am ---Hey, tautech, I think you've got me wrong. I see polar and Cartesian plots on your images.. And what I was saying is that polar plot = Smith chart.

--- End quote ---

Using your logic, polar plot = Smith chart = Cartesian plot.   


--- Quote ---And it's probably how it's implemented on most of VNAs firmware.
--- End quote ---

I have an HP8754A from the 1970s.   It has no firmware.  There are overlays that you insert over the CRT to get the different graph types.   There is a mechanical switch that selects polar or rectangular.

When I wrote the software for it, I map everything to an X-Y graph.  Like the 8754A, I use overlays that map over the top of the X-Y graph.   A technique I still use with my current software. 

pdenisowski:
Coincidentally, I was just using a Smith Chart this morning for a video I'm working on ("Measuring Antennas with the ZPH") so I thought I would share a picture on my "work" Instagram account as well.

https://www.instagram.com/p/C8ZmxqSgWN2

DaJMasta:
When I first got introduced to using smith charts, I found them to be one of the best examples of data visualization in charts that I knew of.  Data visualization, even without analysis, let's us - humans evolved for visual pattern recognition - pull a lot more meaning out of a dataset than when presented as a table, a series of numbers, or some other basic formats.  Your basic trend chart or scatter plot engages our understanding so much more than the raw values, and it's astounding how much useful information is easily gleaned from a smith chart, especially given the relatively modest requirements for plotting data points on one.  A plot that shows impedance matching over frequency that can be normalized to virtually any system impedance, shows meaningful information out towards the extremes, and doesn't just give you match/mismatch information but tells you how so that you can make adjustments to the DUT.

Incredibly practically useful for anyone needing to match RF elements all available at a glance, and the absolute basics of relative match vs. mismatch can be see at a glance by someone with no understanding of reactance or how points are plotted on it.  Really top tier visualization/user interface technology.

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