See the picture.

I calibrated my new NanoVnaV2 with pieces you can see in the photo. Then I connected the Load again on the device and measured it, for fun mostly. There are also female/male adapters to protect the VNA connectors. They were connected during the calibration, too.
The FW? version is 20220301

My question: what are the odd CH0 phase reversals around 1,5GHz. They  are quite unstable, and sometimes there are more of them, sometimes less. I thought that calibrated CH0 phase should be stable and close to to 0. And again the Load calibrator is the same as with calibration.

Leif,
The return signal from the load is (ideally) zero in amplitude, so the (ideal case) phase would be meaningless.  For real instruments and loads the return signal is small and noisy, resulting in poorly defined (noisy) phase.
The open and short standards should give a strong reflected signal with a steady phase.
--John Gord

On Sat, Apr 30, 2022 at 09:59 PM, Leif M wrote:

>
> See the picture.
>
> I calibrated my new NanoVnaV2 with pieces you can see in the photo. Then I
> connected the Load again on the device and measured it, for fun mostly.
> There are also female/male adapters to protect the VNA connectors. They
> were connected during the calibration, too.
> The FW? version is 20220301
>
> My question: what are the odd CH0 phase reversals around 1,5GHz. They  are
> quite unstable, and sometimes there are more of them, sometimes less. I
> thought that calibrated CH0 phase should be stable and close to to 0. And
> again the Load calibrator is the same as with calibration.

I see. But short also gives noise at upper and lower frequencies. Smith chart shows clear dot at open end.
I can't get screen capture with this VNA, but NanoVNA-app shows this

This is what short looks like.

Why strange?

You see small phase noise (jump from 180 to -180 degree). You must understand: 180 and -180 degree equal (i hope).

I thought that after calibration, measuring again calibration standards, every reading would be stable line or or dot.

When calibrating the LOAD, the reflected signal is calibrated to zero. What
phase you think must have that zero signal?

Von meinem Huawei-Telefon gesendet



\-------- Ursprüngliche Nachricht --------
Von: Leif M <leif.michaelsson@gmail.com>
Datum: So., 1. Mai 2022, 13:06
An: NanoVNAV2@groups.io
Betreff: Re: [nanovnav2] Strange phase reading from calibrated load with a new
Nano VNA V2 Plus 4

> I thought that after calibration, measuring again calibration standards,
every reading would be stable line or or dot.

_._,_._,_

* * *

Where a measured signal gets near zero, noise becomes dominant.

On image show phase of short connection. In this case phase near +180 or -180 degree (values equal) so of exist small noise graph jump from -179.9 degree (bottom) to 179.9 (top)