solving K using rollet's stability factor formula

Trying to measure the stability of my LNA. I obtained linear magnitude and phase angle data points for S11, S12, S21, S22 across 500MHZ - 18GHz

data set attached to post.

Using the Rollet's stability formula.

k = 1 |S11|2 - |S22|2 +|Δ|2
----------------------------
2|S21*S12|

where Δ S11S22 - S12S21

My question is now that I have linear data points can I just plug in the linear mag data into the formual to determine if K > 1? Or is there another step Im missing out on.

Please advise

I believe you've been using a lot of stuff out of Pozar's book, the answer should be in there. For the vast majority of his derivations, he uses S-params as linear values (not dBs), so you should be set to crunch the K numbers.

Microwaves101.com is another good resource for general RF topics. The information is very readable and pretty much no-nonsense.
http://www.microwaves101.com/encyclopedia/kfactor.cfm

No, you are not missing anything :) It is exactly as you wrote...