Design and Investigation of a Multifocus Tensor Holographic Impedance Metasurface

In this letter, we propose a period-weighted shared-aperture (PWSA) method to achieve multifocusing using tensor holographic impedance metasurfaces (THIM). A focusing phase expression is derived, and the period of impedance variation is employed as a weighting factor to reconstruct the multifocal impedance distribution. The results demonstrate that the PWSA method enhances electric field intensity while maintaining good focal resolution, even when the number of focal points increases and their positions are closely spaced. A dual-focus THIM composed of 31×31 unit cells was designed, fabricated, and investigated. Both simulation and experimental results demonstrate the superiority of the proposed approach in focusing control compared to the traditional method. Moreover, compared with the traditional method, the PWSA method can obtain 20.3% more power. The simulated and measured results agree well, validating that the proposed technique performs well in multifocus generation.