Far Field of Array with Parabolic Reflectors

Dear All,

if I have an array of 4 Parabolic Reflectors staying close to each other with elements spacing of 100lambda, where starts Far Field of this array?

in the far field of each parabolic antenna or in the far field of array?

thanks in advance.

It is the effective aperture of the array that determines the beginning of the far field.

If it's a squared array it's true
but it it's a rectangular array then the largest side determines the beginning of the far field.