How to design slotted waveguide array

I want to design a slotted waveguide (filled with dielectric) array. Please tell me how to obtain the length and position of every slot if the magnitude and phase of the excitation of slot is known. I want to use the Elliot's three equations, but someone tell me that Elliot's method is not accurate and MoM should be accurately used to design the slotted waveguide array. Since it takes a lont time to simulate a big slotted waveguide array using MoM, I want to know how to get the initial length and positon of every slot and how to effectively tune the length and positon of every slot in the design process by MoM.

Thanks in advance!

the slot size maybe calculate by MoM but design a antenna array need more

efficient method like ray-tracing(GTD or PTD)

the slot size depend on operation frequency but that have some differnt from

mutual coupling.