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can you send as attachment your .s2p file I wrote a little software to smooth out the errors. I would see what happens. -- F1AMM Fran?ois De la part de astech119 Envoyé : lundi 26 juin 2023 18:32

We have a little trouble understanding each other. It is not a question of measurement but of calculation. I have an adapter which for a given input impedance returns the impedance Zout =

I'm measuring the group delay of some 60in cables with a NanoVNAH4 and I am getting outliers in the data. I am using nano-vna saver and I have tried both with on board calibration disabled and

Calibrating with the crocodile clips will not give you a good reference plane. The reason I say this is if you keep them the same distance apart when you cal with an open, short and load you will have

It's possible, that with some active systems, you could get a reflection that is bigger than the incident wave (i.e. if the Zload were negative). But I think that for an entirely passive load, the

My study (amateur) concerns the cascading of 2 adapters in 'L' one high pass and the other low pass to carry out two adaptations of impedance at two different frequencies. To generalize the brought

I knew about the phone lines. My problem is that if we calculate the S11 with complex values, it leads, for example, to a ROS which can be negative. S11 is no longer in a circle of radius 1. Is this

Definitely so. When working w

Sure it is: S11 is just a representation of the reflection coefficient on port 1 of the UUT. Generally people use just the log magnitude in dB, but it has a phase, too. Nothing prevents the Z0 being

Hello In the attached formula (ROS.png), as long as Zo is real, even if Zl is complex, everything is fine and S11 remains in a circle of radius 1. and the ROS is between 1 and infinity. If Zo is

This is my test fixture, calibrated at the croc clips. It's not ideal but I'm limited by the length of the coil. Should be OK at my measurement frequency of 70kHz though! -- Mike

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Roger, the method I suggested requires inductance calculated this way. It yields an accurate coil model over a narrow frequency range. To my surprise, it seemed good enough over the whole 3.5-4 MHz

On Sun, Jun 25, 2023 at 11:04 PM, Roger Need wrote: > > On Sun, Jun 25, 2023 at 02:27 PM, Mike wrote: > > > > > Thank you Roger. The coil is 95 turns of 0.9mm enamelled copper wire close > > wound on

The VNA can only measure R + jX or R//jX (with later firmware versions). It calculates inductance by dividing X by 2*pi*frequency and this ONLY gives an estimate of the true coil L if the coil is air

Mike, Attached is an analysis of your coil using Coil64. The numbers are close to what you measured. For an air wound coil the actual L will not vary much in the frequency range of up to 12 MHz. Note

Thanks for the link Brian. -- Mike

Mike, measure the inductance and series resistance at the model frequency. I believe recent VNA firmware versions can provide these values directly. Otherwise calculate them from R and X. Then create

Thank you Jim. -- Mike

Thank you Roger. The coil is 95 turns of 0.9mm enamelled copper wire close wound on a 36mm PVC former. -- Mike