space and frequency dependent function inverse fourier transform(IFFT)

Hello

I have a function which is position and frequency dependent. I want to plot this function as position and time. So I calculate the ifft of the function. Can anyone help me how to find to convert the frequency to time. After I calculate the ifft how can I find the time? Here is my code. Can i just simply use ifft2 of I need to write a for loop?

close all
clc
clear all

f=linspace(1,8*10^6,100);
x=linspace(1,5,100)';

alpha=(10^-5).*f -20;
beta=2000 + ((2000/pi)^2)*(10^-5)*log(f./(10^6));

H=sqrt(1./x).*exp(-alpha-1i*beta);

ifftofH=ifft2(abs(H));

figure(1)
mesh(f,x,abs(H))

 figure(2)
  mesh(t,x,ifftofH) % how to get the time???

Any help is appreciated.

Thanks GH