Impedance-modulated holographic metasurface for beamforming in the X-band [Invited]

Achieving precise multi-beam or shaped-beam radiation patterns with low sidelobes remains a significant challenge in modern microwave antenna design. Existing leaky-wave antennas often struggle to achieve accurate aperture field control, resulting in performance degradation for complex target fields. In this work, a beamforming microwave antenna, including a monopole feed antenna and a tensor impedance holographic metasurface, is designed to operate around 10 GHz. The concept utilizes the anisotropy of the tensor impedance to achieve nonuniform modulation of the transmission amplitude and phase of the surface and leaky waves on each unit of the metasurface array through an iterative algorithm. The modulation coefficients and the tensor impedance of each unit are calculated through the radiation field, achieving beamforming for different target fields. Dual-beam and flat-top beams can be successfully achieved within a 9.7 GHz-10.3 GHz frequency range, with a gain exceeding 13 dBi and low sidelobes, effectively ensuring the directivity and accuracy of the microwave radiation.