An object-detection system comprising: a phase shifting element array including a plurality of metamaterial structures, each said metamaterial structure configured to resonate at a radio wave frequency of an applied input signal corresponding to incident radiation such that said plurality of metamaterial structures respectively generate output signals having said radio wave frequency wherein the phase shifting element array comprises a three-layer structure including an electrically isolated backplane layer, a blanket dielectric layer (144A-1) disposed over the backplane layer, and multiple spaced-apart metal island structures (141A-1) and a base metal layer co-disposed on an upper surface of the dielectric layer (144A-1), where the base metal layer is spaced from the metal island structures (141A-1) by a gap, wherein each metamaterial structure of the array is formed by one of the metal island structures (141A-1) and an associated backplane layer portion disposed under the metal island structure (141A-1) along with an associated portion of the dielectric layer (144A-1) sandwiched therebetween, wherein the base metal layer is connected to a ground potential; and a beam control circuit configured to use variable capacitors to generate a plurality of variable capacitances and to apply each said variable capacitance to an associated metamaterial structure such that an effective capacitance of said associated metamaterial structure is altered by a corresponding change in each said applied variable capacitance, whereby said plurality of metamaterial structures respectively generate output signals at corresponding output phases determined by said plurality of variable capacitances, wherein the variable capacitors are distributed on the array such that each variable capacitor is connected between an associated metamaterial structure and a shared ground potential, whereby the variable capacitor is mounted across the gap such that a first terminal (151A-1) is connected to an associated island structure and such that a second terminal (152A-1) is connected to the base layer, and wherein said beam control circuit is further configured to vary said plurality of variable capacitances such that said output signals collectively generate a scan beam that sweeps across a field disposed in front of said phase shifting element array. a phase shifting element array including a plurality of metamaterial structures, each said metamaterial structure configured to resonate at a radio wave frequency of an applied input signal corresponding to incident radiation such that said plurality of metamaterial structures respectively generate output signals having said radio wave frequency wherein the phase shifting element array comprises a three-layer structure including an electrically isolated backplane layer, a blanket dielectric layer (144A-1) disposed over the backplane layer, and multiple spaced-apart metal island structures (141A-1) and a base metal layer co-disposed on an upper surface of the dielectric layer (144A-1), where the base metal layer is spaced from the metal island structures (141A-1) by a gap, wherein each metamaterial structure of the array is formed by one of the metal island structures (141A-1) and an associated backplane layer portion disposed under the metal island structure (141A-1) along with an associated portion of the dielectric layer (144A-1) sandwiched therebetween, wherein the base metal layer is connected to a ground potential; and a beam control circuit configured to use variable capacitors to generate a plurality of variable capacitances and to apply each said variable capacitance to an associated metamaterial structure such that an effective capacitance of said associated metamaterial structure is altered by a corresponding change in each said applied variable capacitance, whereby said plurality of metamaterial structures respectively generate output signals at corresponding output phases determined by said plurality of variable capacitances, wherein the variable capacitors are distributed on the array such that each variable capacitor is connected between an associated metamaterial structure and a shared ground potential, whereby the variable capacitor is mounted across the gap such that a first terminal (151A-1) is connected to an associated island structure and such that a second terminal (152A-1) is connected to the base layer, and wherein said beam control circuit is further configured to vary said plurality of variable capacitances such that said output signals collectively generate a scan beam that sweeps across a field disposed in front of said phase shifting element array.