Network-Based Design of Reactive Beamforming Metasurfaces

The paper introduces a microwave network-based technique to design beamforming metasurfaces. The metasurface consists of a grid of unit cells, each connected to a port. The impedance matrix that characterizes the metasurface is computed using a commercial electromagnetic full-wave solver to account for coupling between the unit cell ports. To achieve beam steering and shaping, the ports are terminated with reactive loads optimized through network theory. The metasurface can function either as a directly-fed antenna or reflector by simply changing the reactive loads. This design technique is applied to a metasurface of aperture-coupled unit cells consisting of three layers: a patch, a slotted ground plane, and a microstrip line with ports. The unit cell topology ensures good isolation between the radiated field and the reactive loads. Several design examples are presented and validated through full-wave solver, highlighting the technique’s potential for generating multi-beam metasurface designs.