Patent ID: 8466838

Claim:
A circularly polarized antenna, comprising: (a) a dielectric substrate having a first surface and an opposite, second surface; (b) a conductive ground layer formed on the first surface of the dielectric substrate; (c) a conductive patch on the second surface of the dielectric substrate, the conductive patch having four outermost corners and four sets of four inner corners, the conductive patch defining two rectangular slots, wherein the four outermost corners define a square surface that encompasses entirely a current distribution face of the conductive patch, the current distribution face delivering co-polarized in-phase signals and cross-polarized out-phase signals; wherein each adjacent two of the outermost corners are contained in a respective side the conductive patch; wherein each set of the sets of four inner corners defines a recess at a center of a respective one of the sides of the conductive patch, wherein the each set of four inner corners defines a square face of the recess on the square surface; wherein each of the recesses is sized to substantially reduce the cross-polarized out-phase signals while the antenna is operating at a mode higher than the fundamental mode; wherein the two rectangular slots are orthogonally formed in the central area of the square surface such that one rectangular slot is aligned with one diagonal of the square surface, the other rectangular slot is aligned with the other diagonal of the square surface, and the junction of the two rectangular slots is coincident with the geometrical center of the square surface; and (d) two signal feed ports formed on the conductive patch at a first location and a second location, respectively.