Microwave tunable metasurface with independent wide phase and large amplitude modulation for multifunctional beam control and RCS Reduction

In this paper, a microwave tunable metasurface with independent control of amplitude and phase is proposed. It consists of a varactor diode loaded phase modulation layer, an air spacer, and a PIN diode loaded amplitude modulation layer, all of which are successively cascaded along electromagnetic (EM) propagation. By controlling the equivalent lumped parameters of varactor diodes and PIN diodes independently through bias voltages, modulation of the reflected wave is achieved with 180-degree dynamic phase range and 0.2–0.9 dynamic amplitude range from 4.59 to 4.97 GHz, both of which don't interfere with each other. Additionally, reflected waves under oblique incident angles is conducted to validate the robustness of the design. Designs with diversified lumped parameters and field distributions are further studied in detail. Based on the principle of encoded metasurfaces, three-beamforming, four-beamforming, and radar cross section (RCS) reduction structures are implemented. A 4 × 2 metasurface sample is fabricated and tested in rectangular waveguide, demonstrating the feasibility of this design strategy. This advancement provides new insights for the further development of multifunctional wireless communication systems and radar technologies.