Angularly Stable Metasurface Filter Using a Cloverleaf Element

This paper presents a method to design a single-layer angular stable metasurface (ASM) filter unit cell for a nearly full range of angles of incidence for both TE and TM polarization. We formulate the optimization criterion using the energy balance condition derived from Poynting's Theorem. The proposed unit cell has a “cloverleaf” geometry, and we show that by adjusting the properties of the cloverleaf we obtain the desired angular stability. After optimization we revisit the energy and show how optimization at three points is enough to obtain such balance for the entire angular spectrum.