An antenna comprising: an antenna feed including a coaxial input configured to input a cylindrical feed wave; a double layer feed structure coupled to the antenna feed and having a first layer and a second layer and sides (207, 208), the second layer including a dielectric layer configured to slow a travelling wave relative to a free space velocity, wherein the antenna feed is coupled at a center bottom of the first layer and is configured to input the feed wave into the first layer via the coaxial input, wherein the double layer feed structure is configured such that the feed wave propagates outwardly and concentrically from the antenna feed through the first layer and propagates to and inwardly through the second layer; a radio-frequency, RF, array coupled to and over the second layer and having a plurality of rings of radiating slots configured to interact with the feed wave propagating through the second layer to obtain desired scattering to generate a beam, wherein the RF array further comprises a plurality of patches, wherein each of the patches is co-located over and separated from a slot in the plurality of rings of radiating slots with a second dielectric layer of liquid crystal between each slot of the plurality of rings of radiating slots and its associated patch in the plurality of patches; and a controller coupled to the RF array and configured to apply a control pattern to control radiating slots of a plurality of rings of radiating slots to generate the beam based on application of a voltage to the patch in each patch/slot pair specified by the control pattern, and wherein the radiating slots are configured to be tuned to provide a desired scattering at a given frequency by adjusting a voltage from the controller to steer the beam in accordance with an interference pattern corresponding to a selected beam pattern. an antenna feed including a coaxial input configured to input a cylindrical feed wave; a double layer feed structure coupled to the antenna feed and having a first layer and a second layer and sides (207, 208), the second layer including a dielectric layer configured to slow a travelling wave relative to a free space velocity, wherein the antenna feed is coupled at a center bottom of the first layer and is configured to input the feed wave into the first layer via the coaxial input, wherein the double layer feed structure is configured such that the feed wave propagates outwardly and concentrically from the antenna feed through the first layer and propagates to and inwardly through the second layer; a radio-frequency, RF, array coupled to and over the second layer and having a plurality of rings of radiating slots configured to interact with the feed wave propagating through the second layer to obtain desired scattering to generate a beam, wherein the RF array further comprises a plurality of patches, wherein each of the patches is co-located over and separated from a slot in the plurality of rings of radiating slots with a second dielectric layer of liquid crystal between each slot of the plurality of rings of radiating slots and its associated patch in the plurality of patches; and a controller coupled to the RF array and configured to apply a control pattern to control radiating slots of a plurality of rings of radiating slots to generate the beam based on application of a voltage to the patch in each patch/slot pair specified by the control pattern, and wherein the radiating slots are configured to be tuned to provide a desired scattering at a given frequency by adjusting a voltage from the controller to steer the beam in accordance with an interference pattern corresponding to a selected beam pattern.