ifft plot for S-parameters from EMC simulation

Hello,

I have done ifft of some complex-valued s-parameters obtained from an EMC simulator (FEKO). The goal is to obtain the impulse response from S-parameters. I believe that the ifft is performed correctly. But I have difficulty in scaling the time domain while plotting the ifft results.

Below is what I did:

zpf = 10; %zero-padding factor L = length(S11); % length of s-parameter data set N = 2^nextpow2(L*zpf); %next power of 2 from S11 y = abs(fft(conj(S11),N)/L); % ifft using normalized fft

%%problemtaic part

dt = ((1/frequency(1))-(1/frequency(end)))/20; % time step calculation. frequency(1) = 10.5GHz, frequency(end) = 14.5 Ghz and 20 discrete points of S-parameters are taken from this bandwidth t = (0:dt:(length(y)-1)*dt)*1e9; % time scale for plotting ifft has a length of y

%%end of problematic part

plot(t,log(y));% plotting impulse response in time domain

I need a proper time scale to compare the result with another similar simulation. So, I would like to request for your kind help. Thanks in advance.

Regards, Afroz