Problem about basic array theory

I have a problem asking minimum required seperation between elements of an X band linear phased array operating at 10 GHz employing rectangular waveguide type of radiating elements to be capable of performing 50 degree beam scanning in azimuth.

Then second part of the question is:

If the interelement mutual coupling cannot be ignored, then the active element pattern must be used to determine the overall (composite) array pattern. Give the definition for the active element pattern.

I will be pleased if you help me with this question.

What is your plan of phased array? 4X4? or?

This is a problem to be solved but it does not state details about dimensions or elements of the array