An antenna includes, from top to bottom and bonded together, an upper substrate, a bonding film, a ground plane and a lower substrate. A parasitic patch arrangement and two pairs of radiator arms associated therewith are arranged on an upper surface of the upper substrate. One radiator arm pair are responsive to a differential signal received through respective vias, which extend through the upper substrate, and respective feed lines, which are arranged on a lower surface of the upper substrate, to emit a first radio frequency signal. The other radiator arm pair are responsive to another differential signal received through respective vias, which extend through the substrates, and respective feed lines, which are arranged on a lower surface of the lower substrate, to emit a second radio frequency signal orthogonal to the first radio frequency signal. A gap between one radiator arm pair intersects that between the other pair.