Miniaturized Fractal Reflectarray Element Using Fixed-Size Patch

A Minkowski fractal-shaped patch is proposed for the design of a reduced-size reflectarray element. The intrinsic miniaturization capability of the fractal geometry is fully exploited by leaving unchanged the patch length, while using the fractal scaling factor to obtain a good reflectarray phase agility. The achieved size reduction effect allows to choose array grids with smaller interelement spacing, thus offering the opportunity to have wide-angle scanning capabilities. As validation test, a fractal-shaped X-band reflectarray element, embedded into a 0.3λ×0.3λ cell, is designed to give a high phase agility range, greater than 300°. Furthermore, the design and the experimental validation of a 15 ×15 reflectarray prototype are presented to prove the fixed-beam large angle pointing ability.