Abstract: The antenna element comprises a printed circuit board (1) on one side of which is a conductive ground plane (2); and on the other side of which are two symmetrical conductive feed tracks (3,4) which excite orthogonal slot apertures (12,13, 22, 23) etched in the ground plane. Radiation from the slots induces orthogonal currents into a radiating patch (14, 18) supported in a spaced relationship with the slots. Two signals can be radiated from the patch simultaneously with 90.degree. separation in polarization. The slots radiate to the rear as well as to the front. A symmetrical conductive cavity (17, 25) enclosing the slots contains rear radiation.