A base station antenna, comprising: a panel that includes a ground plane; at least a first array that includes a first plurality of linearly arranged radiating elements (122-1 to 122-11) and a second array that includes a second plurality of linearly arranged radiating elements (142-1 to 142-11) mounted on the panel, wherein the first plurality of linearly arranged radiating elements (122-1 to 122-11) of the first array are spaced apart from the second plurality of linearly arranged radiating elements (142-1 to 142-11) of the second array in a direction perpendicular to a longitudinal axis of the panel; and a decoupling unit positioned between a first radiating element of the first array and a first radiating element of the second array, wherein the decoupling unit is spaced apart from the first radiating element of the first array and from the first radiating element of the second array, and wherein the decoupling unit is configured to reduce cross coupling between the first radiating element of the first array and the first radiating element of the second array, wherein the decoupling unit includes at least a first sidewall that faces the first radiating element of the first array, a second sidewall that faces the first radiating element of the second array, a top plate that connects an upper edge of the first sidewall to an upper edge of the second sidewall, and an internal cavity that is defined in a region between the first and second sidewalls (210, 220), the top plate and the ground plane which extends between lower sides of the first sidewall and the second sidewall, and wherein the first and second sidewalls (210, 220) are each electrically conductive and are electrically connected to the ground plane. a panel that includes a ground plane; at least a first array that includes a first plurality of linearly arranged radiating elements (122-1 to 122-11) and a second array that includes a second plurality of linearly arranged radiating elements (142-1 to 142-11) mounted on the panel, wherein the first plurality of linearly arranged radiating elements (122-1 to 122-11) of the first array are spaced apart from the second plurality of linearly arranged radiating elements (142-1 to 142-11) of the second array in a direction perpendicular to a longitudinal axis of the panel; and a decoupling unit positioned between a first radiating element of the first array and a first radiating element of the second array, wherein the decoupling unit is spaced apart from the first radiating element of the first array and from the first radiating element of the second array, and wherein the decoupling unit is configured to reduce cross coupling between the first radiating element of the first array and the first radiating element of the second array, wherein the decoupling unit includes at least a first sidewall that faces the first radiating element of the first array, a second sidewall that faces the first radiating element of the second array, a top plate that connects an upper edge of the first sidewall to an upper edge of the second sidewall, and an internal cavity that is defined in a region between the first and second sidewalls (210, 220), the top plate and the ground plane which extends between lower sides of the first sidewall and the second sidewall, and wherein the first and second sidewalls (210, 220) are each electrically conductive and are electrically connected to the ground plane.