A new method is introduced to analyze phased array antennas of the aperture type, and is based on the Fourier transform relationship between the aperture electric field's cross-correlation function and the angular cross-spectral power density. The theory is first presented in the general form for planar arrays and then is applied to a linear array of infinitely long narrow slots covered by a dielectric slab. The array input admittance as well as the active reflection coefficient are deduced. It is shown that the point of unit reflection coefficient (blindness) in the scanning pattern, which occurs for ideal infinite periodic arrays, no longer exists for arrays with positioning errors. Instead, a near-zero reflection point is preceded and succeeded by two reflection maxima. The cross-correlation method helps also to clarify the nature of blindness for large finite periodic arrays; again, the blindness angle is one at which there is a near-zero reflection coefficient with two high reflection coefficient regions on either side.