An element assembly has a structure in which insulator layers including first and second insulator layers are laminated in an up-down direction. The first insulator layer is above the second insulator layer. A radiant conductor layer is on an upper surface of the first insulator layer. A first capacitance defining portion includes a first interlayer connection conductor passing through one or more of the insulator layers in the up-down direction. The first interlayer connection conductor is electrically connected to the radiant conductor layer. The radiant conductor layer, a ground conductor, and the first capacitance defining portion define and function as a patch antenna. When the first interlayer connection conductor is electrically connected to the radiant conductor layer, a distance from a lower end of the first interlayer connection conductor to the ground conductor in the up-down direction is shorter than a distance from the radiant conductor layer to the ground conductor in the up-down direction.