Single- and Dual-Band Transparent Circularly Polarized Patch Antennas With Metamaterial Loading

In this letter, we present circularly polarized (CP) patch antennas that achieve up to 70% optical transparency by using a wire-mesh patch and by cutting the same grid pattern through the substrate. Glass or quartz wafers are therefore not needed, and our antennas may be fabricated on standard ceramic substrates, reducing cost and simplifying construction. Metamaterial loading is incorporated in one patch to control the relative phase difference between the patch´s orthogonal modes, which in turn produces dual-band CP radiation. Our dual-band transparent antenna operates at 2.35 and 2.73 GHz with peak radiation efficiencies of 70% and 78%, respectively.