In this paper, we present a novel frequency-selective surface (FSS) design aimed at enhancing the performance of broad-band reconfigurable antenna apertures. In particular, reconfigurable printed dipole arrays are examined in the presence of a multilayer FSS. Of particular interest is the design of FSS structures whose reflection coefficient has prespecified phase response over a broad set of frequencies. Previous FSSs primarily considered designs on the basis of the reflection-coefficient amplitude and were intended for radome applications rather than substrates. Designing FSSs subject to phase requirements will be seen to require some compromise in the magnitude. Broad-band requirements also present us with a need for noncommensurate FSS designs.

A novel dual-band reconfigurable aperture (RECAP) design is introduced for operation over a two-octave bandwidth. The proposed RECAP consists of interleaved crossed-slot elements for dual-polarized and broad-band array operation without grating lobes. The dimensions of the array elements can be reconfigured by using radio-frequency switches such as microelectromechanical systems or PIN diodes. The array elements along with the switches are integrated into the top layer of a multilayered composite structure consisting of passive, resistively loaded frequency selective surface (FSS) elements that form a broad-band ground plane system. Excitation is provided through a broad-band balanced/matched feed, and reconfiguration allows for broad-band operation using the same FSS substrate. Besides the FSS substrate, shorting pins can be employed within the cavity to enhance gain performance. Significant analysis and understanding of the FSS/slot array configuration is presented along with measurements that should serve as a reference in future developments of these layered arrays.Index Terms-Antenna isolation, broad-band balun, broaband substrate, frequency selective surface, mode suppression, reconfigurable aperture, slot antenna array.

No abstract