Investigation of slot reflectarray antennas

Research results of slot metal-only reflectarray antennas are presented in this paper. The analysis is based on both full-wave and unit-cell simulation. The solution is based on the Method of Moments that is applied to integral equations in terms of magnetic-current distribution functions. Reflection phase of one- and two-layer unit cell is considered. The possibility of reflectarray-bandwidth increase by means of element-spacing decrease is investigated. It is shown that under certain conditions a disruptive parasitic mode within the unit cell is excited. A set of geometry parameters that provides reflectarray bandwidth of ~10% (under a criteria of 3dB gain reduction) is determined by theoretical predictions and full-wave simulation. Appropriate geometry configurations have element spacing less than 0.4λ in E-plane. Two samples of one-layer metal-only reflectarray antennas have been fabricated and are currently investigated.