A metamaterial for separating an electromagnetic wave beam is disclosed. Two kinds of man-made microstructures are attached on a substrate of the metamaterial. The first man-made microstructures each have a principal optical axis parallel to a first electric field direction, and the second man-made microstructures each have a principal optical axis parallel to a second electric field direction. The metamaterial comprises a first region and a second region. The first man-made microstructures in the first region have the largest geometric size and the first man-made microstructures in other regions increase in geometric size continuously in a direction towards the first region; and the second man-made microstructures in the second region have the largest geometric size and the second man-made microstructures in other regions increase in geometric size continuously in a direction towards the second region.