How to calculate the frequency response of LTI system based on measured impedance
this is more about electronics, but i think it can be asked here.

when you are looking for a frequency response of an impedance, i believe this means you have a two-terminal (a.k.a. one-port) device.  so, instead of an input voltage and output voltage to relate by a transfer function (and from the transfer function you get a frequency response), what you have is a voltage applied to the two terminals and a current measured, or a current shoved into (and out of) the terminals and the resulting voltage measured.

the complex impedance of the two-terminal device, as a function of frequency, is the frequency response the device assuming current is the input and voltage is the output.  you can plot it on a dB scale, but without a reference resistance, you don't have a reference for 0 dB on that frequency response plot.  but you have relative dB for the different impedances at different frequencies.

maybe ask the EE guys this question.  i dunno.