Autocorrelation Matrix of sub-band

So, I’m dealing with the smart antenna and different DoA algorithms. In order to define narrowband signal directions I have to calculate autocorrelation matrix of this antenna in the frequency domain.

After this I can use MUSIC or ESPRIT algorithm to determine the angles of arrival of the signals.

If I want to work with a wideband signal (signal with wide spectrum) I can use narrowband algorithms for each sub-band, but firstly I have to calculate autocorrelation matrix for this sub-band.

And here is the main question: how it (autocorrelation matrix of sub-band) should be calculated? I have an idea that I can just simply filter spectrum of each receiver of the antenna and then calculate autocorrelation as usual, but I don’t know if it is correct.

Thanks in advance!