An inkjet recording apparatus includes an inkjet head and a frame supporting the inkjet head. First, a capacitive element is formed. Spacers are formed on sidewalls of the gate structure. The width of the conductive flat plate is substantially a multiple of a quarter of a wavelength attained at the operating frequency of the antenna by an odd-numbered value. The method further comprises computing spacing adjustment amounts for the remaining locations relative to the reference location based on the differences in thickness between the reference location and the remaining locations.