An electronically-controlled steerable beam antenna with suppressed parasitic scattering, comprising: a feed line defining an axis x; and first and second arrays (54, 58) of electronically-controlled switchable scatterers (52, 56) distributed along the axis x, each of the scatterers (52, 56) in the first and second arrays (54, 58) being switchable between a high state and a low state to scatter an electromagnetic wave propagating through the feed line so as to form a steerable antenna beam; wherein the switchable scatterers of the first array are distributed along a first side of the feed line, and the switchable scatterers of the second array are distributed along a second, opposite side of the feed line, characterized in that: the switchable scatterers (52, 56) in the first and second arrays (54, 58) are in mirror symmetry with respect to each other relative to the axis x; wherein, as a result of the mirror symmetry, each of the scatterers of the second array that is in the low state is phase-shifted 180 degrees relative to a corresponding scatterer of the first array; and wherein the switchable scatterers (52, 56) of the first and second arrays (54, 58) are configured into high states and low states so as to suppress parasitic scattering of the electromagnetic wave by the low state scatterers without suppressing the steerable antenna beam. a feed line defining an axis x; and first and second arrays (54, 58) of electronically-controlled switchable scatterers (52, 56) distributed along the axis x, each of the scatterers (52, 56) in the first and second arrays (54, 58) being switchable between a high state and a low state to scatter an electromagnetic wave propagating through the feed line so as to form a steerable antenna beam; wherein the switchable scatterers of the first array are distributed along a first side of the feed line, and the switchable scatterers of the second array are distributed along a second, opposite side of the feed line, characterized in that: the switchable scatterers (52, 56) in the first and second arrays (54, 58) are in mirror symmetry with respect to each other relative to the axis x; wherein, as a result of the mirror symmetry, each of the scatterers of the second array that is in the low state is phase-shifted 180 degrees relative to a corresponding scatterer of the first array; and wherein the switchable scatterers (52, 56) of the first and second arrays (54, 58) are configured into high states and low states so as to suppress parasitic scattering of the electromagnetic wave by the low state scatterers without suppressing the steerable antenna beam. the switchable scatterers (52, 56) in the first and second arrays (54, 58) are in mirror symmetry with respect to each other relative to the axis x; wherein, as a result of the mirror symmetry, each of the scatterers of the second array that is in the low state is phase-shifted 180 degrees relative to a corresponding scatterer of the first array; and wherein the switchable scatterers (52, 56) of the first and second arrays (54, 58) are configured into high states and low states so as to suppress parasitic scattering of the electromagnetic wave by the low state scatterers without suppressing the steerable antenna beam.