Cloverleaf- Element Design for Single- Layer Angularly Stable Metasurface Filters

In this work, we present a novel method for designing the unit cell of a single-layer angularly stable metasurface (ASM) for a nearly full range of incidence angles, up to nearly 90 degrees. The optimization criterion is formulated using the resonance condition of balanced electric and magnetic energies, as derived from Poynting's Theorem. The proposed unit cell features a unique 'cloverleaf' geometry, which can be fine-tuned to achieve the desired angularly stable performance. Our analysis reveals that optimizing at three-angle values is sufficient to attain energy balance across the entire angular spectrum. We also present transmission measurements of the obtained metasurface design, which was fabricated from a thin aluminum sheet, and corroborates the theoretical and numerical results. This design can be useful for advanced applications in radar systems, antenna engineering, and emerging electromagnetic technologies.