Holographic-Reflective Metasurface for Independent Control of Surface and Space Waves

In this letter, a holographic-reflective metasurface (HRM) is proposed for independently controlling of surface waves (SWs) and spatially propagating waves (SPWs) at the same operating frequency. The meta-atom consists of four holographic sub-cells that determine the surface impedance for SW-to-radiation conversion, together with a reflective structure whose length defines the phase of the reflected SPW. Three prototypes, including a multi-beam HRM and two low radar cross section (RCS) HRMs are designed. The measured results show that the low-RCS HRMs achieve beam steering and RCS reduction. The multi-beam HRM is capable of generating a directional beam in the holographic mode and a conical beam in the reflection mode, achieving a peak broadside gain of 17.5 dBi and a radiation null depth of 22 dB.