I am strugling with how to compute the exact value of delay in time-doamin when knowing phase shift in frequency domain. I have a analog circuit, I sweeped about 30 single tones frequency ranging from 250 MHz to 8 GHz, and achieved amplitude (A) and phase ($\phi$) response of the circuit. I then used that transfer curve (denoted H) (combining amplitudes and phases) to generate response in time-domain (denoted h) using iFFT. Finally, I want to confirm that the h is correctly constructed by taking convolution of a single tone with that h to compare the output power and phase. However, I observed some phase shifts. For sinstance, the phase rotated a value of [65 degree + 2.3*n], where n= [0, 1, 2,.. 30]. I know that that the phase rotation in frequency domain will induce a delay tin time domain, and I need to include that delay when doing verification process. But, I do not know how to estimate the delay in time-domain. Please help me with this issues.
Thank you verymuch.