Patent ID: 8134521

Claim:
An electronically tunable microwave reflector, comprising: a ground plane, the ground plane having a ground plane surface; an array of generally flat, circular disk metal electrodes arranged in a single layer of rows and columns in a two-dimensional lattice spaced vertically from the ground plane surface by a distance less than a wavelength of microwave energy to be reflected by the reflector, the electrodes having a diameter less than said wavelength, each of the electrodes being adjacent to up to two of the electrodes in a same one of the rows, adjacent to up to two of the electrodes in a same one of the columns, and diagonal to up to four of the electrodes in adjacent ones of the rows and columns; a corresponding array of vertical three-dimensional conductor-free regions above the ground plane and between diagonal electrodes, the regions having a lattice cross-sectional area of at least one-half that of the electrodes; a plurality of variable capacitance structures arranged for controllably varying a capacitance between adjacent ones of said electrodes; a first array of conductors connecting a first set of the metal electrodes to the ground plane surface; and a second array of conductors connecting a second set of the metal electrodes to respective bias voltage sources.