An array antenna comprising: a plurality of dual-polarized slot antenna elements (11a-f), each of the plurality of dual-polarized slot antenna elements comprising: a horizontal board element (16a-f) having a radiating portion having one or more notch antenna elements (20a, b) disposed thereon and a having feed portion having a feed circuit disposed thereon and configured to provide signals to each of the one or more notch antenna elements disposed on the radiating portion of the horizontal board element and having a receiving slot provided in a first one of the radiating or feed portions of the first horizontal board element; a vertical board element (18a-f) having a radiating portion having one or more notch antenna elements (20c, d) disposed thereon and having a feed portion having a feed circuit disposed thereon and configured to provide signals to each of the one or more notch antenna elements disposed on the radiating portion of the vertical board element and having a receiving slot provided in a second one of the radiating or feed portions of the vertical board element with the receiving slot of the horizontal board element engaged with the receiving slot of the vertical board element such that the horizontal and vertical board elements are interleaved and are orthogonally disposed; said array antenna being characterized by further comprising an upper ground block and a lower ground block coupled to the plurality of dual-polarized slot antenna elements, wherein the upper ground block and the lower ground block provide a ground continuity for the array antenna wherein the upper ground block and the lower ground block comprise respective ground planes that sandwich the horizontal board element feed portion and the vertical board element feed portion of each of the plurality of dual-polarized slot antenna elements. a horizontal board element (16a-f) having a radiating portion having one or more notch antenna elements (20a, b) disposed thereon and a having feed portion having a feed circuit disposed thereon and configured to provide signals to each of the one or more notch antenna elements disposed on the radiating portion of the horizontal board element and having a receiving slot provided in a first one of the radiating or feed portions of the first horizontal board element; a vertical board element (18a-f) having a radiating portion having one or more notch antenna elements (20c, d) disposed thereon and having a feed portion having a feed circuit disposed thereon and configured to provide signals to each of the one or more notch antenna elements disposed on the radiating portion of the vertical board element and having a receiving slot provided in a second one of the radiating or feed portions of the vertical board element with the receiving slot of the horizontal board element engaged with the receiving slot of the vertical board element such that the horizontal and vertical board elements are interleaved and are orthogonally disposed; said array antenna being characterized by further comprising an upper ground block and a lower ground block coupled to the plurality of dual-polarized slot antenna elements, wherein the upper ground block and the lower ground block provide a ground continuity for the array antenna wherein the upper ground block and the lower ground block comprise respective ground planes that sandwich the horizontal board element feed portion and the vertical board element feed portion of each of the plurality of dual-polarized slot antenna elements.