An antenna device includes a substrate having a first surface and a second surface. A first conductive layer is formed on the first surface of the substrate, the first conductive layer having a perimeter defined by one or more shapes having straight or curved edges. The first conductive layer defines a slot and a coupling gap, and also includes a top ground. The coupling gap separates the top ground from a metal plate region. A second conductive layer is formed on the second surface of the substrate, the second conductive layer including a bottom ground. The slot, coupling gap, first conductive layer, and substrate form a composite right and left handed (CRLH) structure.