An antenna is disclosed. The antenna comprises a feedline (101), a ground plane (102) and a radiator (103). The feedline has a path in a first plane, the path having a first arm (1011) and a second arm (1012) perpendicular to the first arm. The ground plane is provided in a second plane spaced apart from, and parallel to, the first plane. The ground plane has a ground plane slot (1021) therein with a path in the second plane. The path of the ground plane slot intersects the path of the feedline at a first position on the first arm and a second position on the second arm when the second plane is projected into the first plane. The radiator is separated from the feedline by the ground plane, and is provided in a third plane spaced apart from, and parallel to, the second plane.