Study of the behaviour of a two layered high impedance surface with electromagnetic band gap

High impedance surfaces (HIS), well described in [1], are well known to suppress surface waves and thus to improve the isolation of radiating elements in an array. A Controlled Radiation Pattern Antenna (CRPA) generally consists of an array of a few elements separated by a physical distance of about half a free space wavelength [2]. The available space between the elements of the array is a critical parameter. Although the metamaterial unit cells of the HIS are very small compared to the wavelength, typically below λ0/10, only a few rows of these structures can be inserted between the elements. Thus a compromise between mutual coupling reduction and the inter-element distance has to be made.