The limiting factor is mutual H-plane coupling in a close spaced planner array. The higher the elements the greater the spacing required between elements. Minimum edge spacing for 20 dB isolation between elements is 0.12 wavelength for a height of 0.04 wavelength. Use coaxial not stripline feed. Patch antennas and striplines are not compatible on the same dielectric material.
Strip lines prefer a high dielectric substrate and minimum height to work properly.
With these rules in mind a 0.435 GHz six element circular patch array was designed for the Phase 3D Spacecraft. They are supported by a central grounding post and a dielectric honeycomb under each element. Each element is operated in a RHCP mode. The original, and most basic of these six element arrays is a hexagonal pattern. With equal power to all elements, the array is set for maximum gain.