A Reconfigurable Phase Gradient Metasurface Rasorber Offering Enhanced Beam Steering Capability and a Tuneable Transmission Band

A reconfigurable phase gradient metasurface (PGMS) rasorber design is presented that can provide antenna beam steering and wideband absorption. By creating a varactor loaded, three-layer frequency selective surface (FSS), and individually biasing the adjacent columns, a reconfigurable PGMS can be formed. Then, by further adding a resistive layer with embedded varactors above this PGMS, the structure also becomes a tuneable rasorber with adjustable absorption bands. As further shown in the paper, the PGMS rasorber can steer a beam from broadside by 30 degrees in either direction, with the ability to tune to intermediate angles by modifying the gradient of the PGMS. Furthermore, by applying a common bias to the columns, the structure can also operate as a rasorber with a tunable transmission band between 4.1 and 6.4 GHz. To the best knowledge of the authors, no similar multi-functional design achieves combined reconfigurable beam steering and absorption. Some applications include radar scenarios and phased arrays, where the metasurface could be used to minimise mechanical steering or phase shifting requirements, while also, reducing scattering.