Miniaturized Dual-Band CPW-Fed Antennas Loaded With U-Shaped Metamaterials

New dual band miniaturized planar antennas loaded with 4-cell metamaterial is presented. The structure of the antenna consists of a coplanar waveguide at input, microstrip line, patch, metamaterial loaded substrate under patch, and back conductor. For simpler construction procedure, U-shaped and inverted U-shaped metamaterial loaded substrate under the patch is made in two layers. At the first band, these antennas work as a wideband monopole antenna with about 35% miniaturization compared to the folded monopole antenna, and at the second band as a wideband patch antenna with about 77% miniaturization compared to the conventional patch antenna.