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Re: testing non-50 ohm filters was Re: [nanovna-users] NanoVNA port renormalization

 

Nizar,
I put series 390 ohm resistors on both port 0 and port 1, creating a 440 ohm environment for the filter, close to the 430 ohm renormalization I showed before (see message 39460).
I then normalized the S21 measurement by connecting the two resistors end for a thru measurement.
Attached is the filter S21 magnitude in the 440 ohm environment. It matches very well with the Z=430 renormalized measurement I posted before, allowing for the loss in dynamic range due to the resistors.
--John

On Fri, Feb 14, 2025 at 10:28 AM, Team-SIM SIM-Mode wrote:


Hi

it seems to me that for a linear or quasi-linear circuit without active
elements, it should be correctly compensated by single precision floating
point calculation using the Z renormalization option and this with the
simplest possible hardware tricks during the measurements, thus avoiding
hardware imperfections of the ferrite core or resistance transformers and
without any calibration alteration.

May be Jhon can illustrate for us response comparaison between H4+Z
renormalization and oxilloscope classic measurements of the same ceramic
filter. it will be very appreciated.

73's Nizar .

5.bmp

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