A nonplanar metamaterial polarizer includes: a substrate including dielectric material transmissive to electromagnetic radiation and having a nonplanar shape; a first conductive pattern on a first side of the substrate; and a second conductive pattern on a second side of the substrate. The first and second conductive patterns are configured to alter the polarization of the electromagnetic radiation as it transmits through the substrate. In some cases, the first and second conductive patterns include split-ring resonators, and the nonplanar shape is a cylinder. An antenna system includes the nonplanar metamaterial polarizer and an antenna inside or adjacent to the nonplanar metamaterial polarizer and configured to transmit or receive the electromagnetic radiation through the nonplanar metamaterial polarizer while the nonplanar metamaterial polarizer alters the polarization of the transmitted or received electromagnetic radiation. In some cases, the antenna is a monopole antenna, a dipole antenna, a biconical antenna, or a discone antenna.