Find in Library

Abstract In this letter, the critical frequency of the periodic metasurface in a dielectric half‐space is studied. First, according to the mode expansion theory, the wave of the periodic metallic elements can be decomposed into different eigen‐modes. Then, as the frequency increases, partial high‐order modes are excited by the periodic metallic elements that may propagate into the substrates as spics. Finally, the critical frequency is analytically derived for a homogenized surface without spics. This study shows that the reflected and transmitted spics can co‐exist, but there is a distinct difference between their corresponding critical frequencies. Thus, the actual critical frequency of homogenized metasurface in a dielectric half‐space is not only related to the periodicity and incident angle, but also to the substrates.