Hi,

When I look at a cal report on my ecal it shows source match, reflection tracking, and directivity all at low rho values along with worst per frequency segment.

Another section shows measurements of the ecal parameters - not asking about that.

When I extract the residuals from the calibration of the e8361a in real,imaginary the vector of the source match and directivity are also low rho values but the reflection tracking term vector is near 1. I've noted specs are also different directivity and source match xx db reflection tracking 0.0x db.

This doesn't seem to impact differences between calibrations using different cal kits, but I'd like to use the RT term in a one port uncertainty equation to see the effect of changes over time and with connector wear.

How should I convert the real img RT data to multiply with rho measured plus directivity plus source match rho^2.

Thanks,

Karl

When I look at a cal report on my ecal it shows source match, reflection tracking, and directivity all at low rho values along with worst per frequency segment.

Another section shows measurements of the ecal parameters - not asking about that.

When I extract the residuals from the calibration of the e8361a in real,imaginary the vector of the source match and directivity are also low rho values but the reflection tracking term vector is near 1. I've noted specs are also different directivity and source match xx db reflection tracking 0.0x db.

This doesn't seem to impact differences between calibrations using different cal kits, but I'd like to use the RT term in a one port uncertainty equation to see the effect of changes over time and with connector wear.

How should I convert the real img RT data to multiply with rho measured plus directivity plus source match rho^2.

Thanks,

Karl

If you had a perfect VNA, the reflection tracking would be 1 +j0, and the directivity and source match would be 0+j0.

So, when we talk about dB error for reflection tracking we say it is 20 Log (RT) and the answer is in units of small dBs like .1 or .2 dB.

For source match and load match, a small number like 0.01+j0 woudl be 20 log (mag (d))=-40 dB.

So reflection tracking should be close to 1 (0 dB) and SM and LM should be close to 0 (-infinite dB)

Roughly speaking, the refection measurement is D + rho*RT+ rho*M^2.