An antenna is described. This antenna includes: a ground plane; and antenna elements that are positioned in a first horizontal plane offset along a vertical direction from the ground plane. Moreover, the antenna elements are configured to generate a beam having a horizontal polarization. Furthermore, the antenna includes a planar reflector that is positioned in a second horizontal plane offset along the vertical direction from the first ground plane, so that the antenna elements are positioned between the ground plane and the planar reflector. During operation, a first reflection from the ground plane, the beam from the antenna elements, a second reflection from the planar reflector and diffractions from edges of the ground plane and the planar reflector combine to generate an antenna radiation pattern having a main beam approximately in a horizontal direction, e.g., at 10-15° from the horizontal direction.