rf grounding system
Is this for the antenna efficiency or protection from lightning and mains faults?
In order of simplicity, the mains fault protection is specified by the laws in your country. Follow them and all will work properly.
For lightning protection, the wire from the lightning rod to the ground system should be straight with no inductive type bends or coiling. The ground system can be a set of buried wires below the surface of the earth.
For the antenna efficiency, it is the sheet resistance of the surface of the earth that must be reduced. First choice is a metal grid like metal fences covering the whole area within several wavelengths of the antenna. Next best is wires going out in all directions from directly under the antenna.