An antenna comprises at least one antenna element arranged in a recess of a ground conductor. A wall of the recess is arranged so that the recess tapers outward from a narrow base inside the recess to a broader mouth. The wall is configured to provide a ground plane for the at least one antenna element. The at least one antenna element comprises a conductive plate arranged perpendicular to the mouth of the recess and to the wall and arranged to provide a slot between the edge of the at least one antenna element and the wall of the recess.
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