Reflectarray and design method

A reflectarray configured to reflect an incident wave in a desired direction, the reflectarray comprising:

• a substrate that includes a surface which is perpendicular to a predetermined axis;
• and
• a plurality of elements disposed on the substrate,
• wherein a specific element among the elements is configured to reflect the incident wave with a specific reflection phase among a plurality of reflection phases,
• wherein each of the elements has a mushroom-like structure, wherein the mushroom-like structure includes a patch, a gap between the patch and the ground plate, and a via hole,
• wherein element spacing between neighboring elements among the elements is a distance between the via holes of the neighboring elements,
• wherein the element spacing of first neighboring elements among the elements is different from the element spacing of second neighboring elements among the elements, and a length of a gap between the patches of the first neighboring elements is equal to a length of a gap between the patches of the second neighboring elements,
• wherein the element spacing is variable, and
• wherein the mushroom-like structures are configured so that the gaps among the patches of the mushroom-like structures can be simultaneously changed by a same value, so as to change the reflection phases.