The Evolution of Antenna Technology: Artificial impedance surfaces.

This article reviews and expands the use of artificial impedance surfaces (AISs), which do not exist in nature but can be synthesized, as ground planes for radiating elements, and in particular, dipoles and loops. It then illustrates that when such surfaces are incorporated with radiating elements, they can enhance the radiation’s characteristics, such as reflection coefficient, gain, realized gain, and pattern symmetry. This is accomplished by the proper design of the metasurface, leading to the enhancement of the radiating elements’ impedance matching, suppression of ground plane surface waves, and reduction of ground plane edge diffractions. These improvements are achieved only over a band-limited frequency range.