Width-Modulated Microstrip Line Unit Cell: A Basic Element for Dispersion Engineered Surfaces for Reflectarray and Holographic Applications

Dispersion characteristics of different classes of width-modulated microstrip line based unit cells forming High Impedance Surfaces (HISs) are investigated. The HISs consist of a periodic arrangement of macro unit cells, formed by sequential repetitions of similar elementary unit cells. Within the single unit cells, mono- and multi-layer metallization configurations are proposed and numerically characterized, which lead to interesting phenomenon of controlling the position and width of the band-gap and provide a key element for efficient dispersion engineering. The effects of the modulation on periodic and quasi-periodic structures are discussed. The modulation parameter of the different metallization within the macro unit cells are changed, which allows competently controlling the reflective phase over a wide frequency band. The proposed modulation mechanism is well suited for the synthesis of reflectarrays and/or holographic surfaces.