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s11 measure in series mode between the channels.

Those interested in more detail on my last post will find this article informative. The graphs at the end show what should be expected when making measurements of characteristic impedance of coaxial

Nizar, What I pointed out in my previous post is that your characteristic impedance measurements were not in accordance with well defined transmission theory. Your results showed a rise in

Yes, they can be pretty good for testing at HF if properly chosen and measured. That's exactly what I do to "quailfy" potentiometers for use at HF frequencies. It works! Dave - W?LEV

Hi Dave To be Honest , this is graphical results of my used potentiometre illustrated with NanoVNA attached screenshoots : +j3 Ohm max at 30Mhz 73's Nizar .

Any potentiometer used in the process can easily be verified to be non-inductive using the VNA. That's how I choose the proper potentiometer. Dave - W?LEV [email protected]> wrote:

This is a s21 measure with DUT in series with the channels. At DC low freq begins at 50 then goes anti resonant and above that an array of parasitic responses.

Hi Dave Here My graphical illustrations of : 1) a 50 Ohm resistor thru a 1/1 balun Zc = 62 Ohm : real & X values change just a bit cross the 30Mhz band. 2) Same 50 Ohm resistor thru a 1/1 balun Zc=142

Here are the images. Brian

Here's another issue revealed by trace dots. The data is for a Johanson 390 nH inductor. Note the trace gap at about 7 o'clock. The frequency steps are uniformly 1 MHz so the gap is not due to a

Hi Roger Thanks, its not assumed that test terminaison resistor should be a pure real resistive value nor an accurate Zc muched impedance but just to be approximatly reduced to a relatively focused

Another suggestion: Make the chart so that the outer boundary circle is say 1.5:1 or 2:1. I have a chart that is either 1.5:1 or 2:1 somewhere in my clutter.

Your measurements do not agree with the calculated values for typical RG213. The characteristic impedance of Belden coax is around 50.6 ohms at 1 MHz and slowly decreases to about 50 ohms at 100 MHz.

Only one of the methods I presented involved a formula. What the dickens is wrong with a little very simple algebra?? The other two methods are simple and only need a non-reactive potentiometer, a

Hi Dave I believe that everything I have presented here has already been demonstrated both experimentally and graphically, without relying on formulas or theoretical estimations. Nevertheless,

QUOTE: In such a case, the measurements will be distorted by the transformation introduced by the CRC's twin-lead line. These CMCs are not made of just "twin lead line". They are intelligently chosen

QUOTE: ........ but should we ever be concerned that CMC might have fc different from the rest of the system? All my CMCs are home brewed and meticulously measured with professional instruments. My

Hi Miro I believe you asked the right question here. In my opinion, not having the correct characteristic impedance (Zc) for the CRC that matches the Coax/Antenna system slightly alters the impedance

12, 10, and 6 meters might be a bit of concern. But usually these are at or less than an electrical 0.1 wavelengths long. The characteristic impedance of all that I've built and measured (well over

Assuming that "wires" (transmission line) used to make CMC are much shorter then "lambda" across useful frequencies, how much impact do you expect from "mismatched" characteristic impedance of CMC?