The customArrayGeometry object can be used to create any 2D structure with multiple feeds. The example given on the page makes it clear how to use it. The documentation, though, is not complete as it says FeedLocation is a 3-element vector, when it can actually be a Nx3 element matrix (as given in the example). If you have the mesh of it as an stl file, then use customArrayMesh.
This page contains everything you need to know about such things (fortunately, the documentation has improved)
If you're trying to model something similar to (but different from) a patch antenna on a substrate, I guess using a pcbStack is much more appropriate. When using a pcbStack object, you can specify as many feed locations as you want.
Looking at what you're trying to do, it appears that you should be creating a 2-element linearArray of patchMicrostrip elements, which gets it done pretty neat (and not cumbersome).
Perhaps this question is too old, but I decided to answer it anyway because someone else might need it.
Hope it Helps!
