{"id":1111,"date":"2015-01-27T10:17:34","date_gmt":"2015-01-27T08:17:34","guid":{"rendered":"http:\/\/new.rigexpert.com\/ja\/transmission-line-measurement-with-zplots\/"},"modified":"2016-12-09T12:55:35","modified_gmt":"2016-12-09T12:55:35","slug":"transmission-line-measurement-with-zplots","status":"publish","type":"post","link":"https:\/\/old.rigexpert.com\/ja\/transmission-line-measurement-with-zplots\/","title":{"rendered":"Transmission line measurement with Zplots"},"content":{"rendered":"

Thanks to the wonderful Zplots software<\/a>, we can measure most important parameters of a transmission line quickly and easily.<\/p>\n

What we might like to know is:<\/p>\n

1) Characteristic impedance versus frequency;
\n2) Velocity factor versus frequency;
\n3) Cable loss versus frequency.<\/p>\n

All we need is getting access to the far end of our transmission line so we can measure both open and shorted cable.<\/p>\n

In this example, I used a RigExpert AA-170 antenna analyzer<\/a> connected to 12.8 meters of the RG-58C\/U cable.<\/p>\n

First of all, an open cable was measured by using the AntScope program, from 10 kHz to 170 Mhz with 1000 points. I save the result as “open1.s1p” file by using the following menu: File – Export – Touchstone – S,MA . Another measurement were done with a shorted cable, the result was saved to “short1.s1p”.<\/p>\n

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“Open” and “short” graphs in AntScope:<\/p>\n

\"\"<\/div>\n

 <\/p>\n

\"\"<\/div>\n

Before opening Zplots, I had to enable macros in Excel so the program can work. At the Smith tab of the Zplots, I pressed the “Measure TL Params” button:<\/p>\n

\"\"<\/a><\/div>\n

I then had to press Yes to confirm:<\/p>\n

\"\"<\/div>\n

In the next window, I entered the length of my cable and pressed OK:<\/p>\n

\"\"<\/div>\n

I was then asked for two files, and I selected “open1.s1p” and “short1.s1p” which I previously saved in AntScope.<\/p>\n

Voila! I could now study the result.<\/p>\n

Characteristic impedance (|Z0|):<\/p>\n

\"\"<\/a><\/div>\n

Please notice that the |Z0| is not a smooth line due to various effects. The average value is displayed in numerical form at the bottom-right corner of the Zplots:<\/p>\n

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Velocity factor (VF):<\/p>\n

\"\"<\/a><\/div>\n

Notice that the velocity factor sufficiently drops at frequencies lower than approximately 1 MHz.<\/p>\n

Cable loss (Loss\/100ft):<\/p>\n

\"\"<\/a><\/div>\n

In addition to displaying the graph, the program calculates coefficients K0, K1 and K2:<\/p>\n

\"\"<\/div>\n

You may use these coefficients in other programs (such as AntScope) as characteristics of your cable.<\/p>\n

See also: Transmission Line Measurement Techniques by KN5L<\/a><\/p>\n

Denis UR8US (ex UU9JDR)<\/p>\n

27-Jan-2015<\/p>\n","protected":false},"excerpt":{"rendered":"

Thanks to the wonderful Zplots software, we can measure most important parameters of a transmission line quickly and easily. What we might like to know is: 1) Characteristic impedance versus frequency; 2) Velocity factor versus frequency; 3) …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"content-type":""},"categories":[63],"tags":[],"_links":{"self":[{"href":"https:\/\/old.rigexpert.com\/ja\/wp-json\/wp\/v2\/posts\/1111"}],"collection":[{"href":"https:\/\/old.rigexpert.com\/ja\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/old.rigexpert.com\/ja\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/old.rigexpert.com\/ja\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/old.rigexpert.com\/ja\/wp-json\/wp\/v2\/comments?post=1111"}],"version-history":[{"count":1,"href":"https:\/\/old.rigexpert.com\/ja\/wp-json\/wp\/v2\/posts\/1111\/revisions"}],"predecessor-version":[{"id":1440,"href":"https:\/\/old.rigexpert.com\/ja\/wp-json\/wp\/v2\/posts\/1111\/revisions\/1440"}],"wp:attachment":[{"href":"https:\/\/old.rigexpert.com\/ja\/wp-json\/wp\/v2\/media?parent=1111"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/old.rigexpert.com\/ja\/wp-json\/wp\/v2\/categories?post=1111"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/old.rigexpert.com\/ja\/wp-json\/wp\/v2\/tags?post=1111"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}