An apparatus comprising: a plurality of radiating elements lying in an X-Y plane, wherein each radiating element in the plurality of radiating elements comprises a number of surface wave channels (1212,1213) in which each of the number of surface wave channels is formed of a plurality of metallic strips (1214, 1224) and a plurality of varactors (1215, 1226) electrically connected to the respective plurality of metallic strips and is configured to constrain a path of a surface wave; and a plurality of surface wave feeds (1210,1211), wherein a surface wave feed in the plurality of surface wave feeds is configured to couple a surface wave channel in the number of surface wave channels of a radiating element in the plurality of radiating elements to a transmission line (1206,1208) configured to carry a radio frequency signal wherein the plurality of radiating elements and the plurality of surface wave feeds form an artificial impedance surface antenna, AISA, that can be electronically steered in a theta direction and a phi direction; a voltage controller configured to control voltages applied to varactors (1215,1226) in the plurality of radiating elements to control a theta steering angle of a main lobe of a radiation pattern formed by the artificial impedance surface antenna; a phase shifter configured to control a relative phase difference between the plurality of surface wave feeds (1210, 1211) to control a phi steering angle of the main lobe of the radiation pattern formed by the artificial impedance surface antenna; wherein the metallic strips of a first surface wave channel of a radiating element of the plurality of radiating elements are periodically arranged at an angle of about positive 45 degrees relative to an X-axis, and the metallic strips of a second surface wave channel of the radiating element are periodically arranged at an angle of about negative 45 degrees relative to the X-axis, wherein the X-axis is the longitudinal axis along the radiating element along which the plurality of metallic strips is distributed. a plurality of radiating elements lying in an X-Y plane, wherein each radiating element in the plurality of radiating elements comprises a number of surface wave channels (1212,1213) in which each of the number of surface wave channels is formed of a plurality of metallic strips (1214, 1224) and a plurality of varactors (1215, 1226) electrically connected to the respective plurality of metallic strips and is configured to constrain a path of a surface wave; and a plurality of surface wave feeds (1210,1211), wherein a surface wave feed in the plurality of surface wave feeds is configured to couple a surface wave channel in the number of surface wave channels of a radiating element in the plurality of radiating elements to a transmission line (1206,1208) configured to carry a radio frequency signal wherein the plurality of radiating elements and the plurality of surface wave feeds form an artificial impedance surface antenna, AISA, that can be electronically steered in a theta direction and a phi direction; a voltage controller configured to control voltages applied to varactors (1215,1226) in the plurality of radiating elements to control a theta steering angle of a main lobe of a radiation pattern formed by the artificial impedance surface antenna; a phase shifter configured to control a relative phase difference between the plurality of surface wave feeds (1210, 1211) to control a phi steering angle of the main lobe of the radiation pattern formed by the artificial impedance surface antenna; wherein the metallic strips of a first surface wave channel of a radiating element of the plurality of radiating elements are periodically arranged at an angle of about positive 45 degrees relative to an X-axis, and the metallic strips of a second surface wave channel of the radiating element are periodically arranged at an angle of about negative 45 degrees relative to the X-axis, wherein the X-axis is the longitudinal axis along the radiating element along which the plurality of metallic strips is distributed.