Hi All!

I want to relize this simple Test in Two diffrent Ways:

1Way:*Without calibrating the VNA*

I took a Variable Damping element (between 0.....50dB). I took a Reference measurement at 0dB. After that i took diffrent measurennts ( 10 dB, 20dB and 50dB). I substract the Reference Measurement from the last measurements. so I got 10dB 20dB and 50dB:

2 Way:*Witth calibration of the VNA*

i got the Same Results.

I know the second Way is Better than the first way, but i dont know why.? is there any help.

I apreciate it.

Thank u.

I want to relize this simple Test in Two diffrent Ways:

1Way:*Without calibrating the VNA*

I took a Variable Damping element (between 0.....50dB). I took a Reference measurement at 0dB. After that i took diffrent measurennts ( 10 dB, 20dB and 50dB). I substract the Reference Measurement from the last measurements. so I got 10dB 20dB and 50dB:

2 Way:*Witth calibration of the VNA*

i got the Same Results.

I know the second Way is Better than the first way, but i dont know why.? is there any help.

I apreciate it.

Thank u.

> Hi All!

>

> I want to relize this simple Test in Two diffrent Ways:

>

> 1Way:*Without calibrating the VNA*

> I took a Variable Damping element (between 0.....50dB). I took a Reference measurement at 0dB. After that i took diffrent measurennts ( 10 dB, 20dB and 50dB). I substract the Reference Measurement from the last measurements. so I got 10dB 20dB and 50dB:

>

>

> 2 Way:*Witth calibration of the VNA*

> i got the Same Results.

>

>

> I know the second Way is Better than the first way, but i dont know why.? is there any help.

>

> I apreciate it.

> Thank u.

You should say what VNA you have, and probably firmware too. I don't know what a varying damping element is.

The hardware in VNA is "reasonably" good. The ports are reasonably matched to 50 Ohms. The coupler has reason directivity.. For some models the frequency response is reasonably flat.

By method #1 you are doing a reasonable job at correcting the frequency response, but imperfections in the match at the ports, the directivity of the coupler is not corrected.

By doing a calibration, with know standards, the VNA measures them and is able to determine its own errors. When a measurement is made, with error correction enabled, the VNA corrects the errors before displaying the results.

A GPS / Satellite Navigation system can tell you the speed and direction you are travelling. Armed with thay information, you could correct the speedo and compass in your car. Since both magnitude and direction is corrected, you have performed a vector error correction, as VNA does.

That's a simplified explanation. You will find a better description in many application notes.