Problems with IFFT

Hi,

I'm kind of newbie in Matlab so I want to excuse wether the q=FCestion
is too simple...

I'm working with a link of two antennas and I want to obtain the ifft
of a parameter. With an antenna design software I obtain the amplitude
and phase in the frequency domain of such parameter. Then I have to
construct the complex parameter with the amplitude and phase and
finally I have to apply the ifft. If my frequency domain goes from
fmin (different from 0 Hz) to fmax with a certain fstep, when I apply
the real(ifft(parameter)) I have to add zeros to the complex parameter
in the frequency domain from 0 Ghz to fmin and after apply the
real(ifft(parameter))? Can I apply it directly or I have to do
something else before? And how is the time domain, that is, when I
obtain the ifft I don't know how to find out tmin, tmax and tstep, the
time axis. The number of samples plays a role, I suppose...

Thanks a lot in advance.

Sandra F.R.