frequency response function , transfer function and natural frequencies

Hi, how can I find the transfer function that would give me a frequency response with two peaks, one at about 4 Hz, that is, the highest one, and the other at 26 Hz? 4 and 6 are the natural frequencies

[Mathieu NOE]

hello Federico

juts for clarification, are you talking about measured data (to be passed to tfestmate) or generating from scratch a second order IIR model with poles at 4 and 26 Hz ?

[Mathieu NOE]

hello

problem solved ?

[Federico Paolucci]

hi, Yes I did