A diamond substrate and a method for fabricating the same are provided wherein a SiC layer is formed on a lower surface of a diamond layer for preventing the diamond layer from being deformed after the process of forming the diamond substrate, and then a semiconductor layer is formed on the diamond layer or directly formed on the surface of the SiC layer. A lock post has an interior end fixed in the housing and an exterior end extruded out of the housing via the hole. The first switch may include one end coupled to a ground and another end coupled to at least one of the plurality of cable elements of the linear array antenna unit.