Dual-Resonance Dynamic Metasurface for Independent Magnitude and Phase Modulation

Cascaded dynamic metasurfaces with multiple control points promise augmented capabilities but have received little attention to date owing to complexity in design. The inclusion of multiple control knobs within a single surface offers more degrees of freedom, which can be optimized---jointly with the static geometry---to provide added functionality. We study a cascaded system with two dynamic layers, each possessing patchlike elements that can be tuned with a varactor diode. A resistor is additionally included to add asymmetry in the resonance loss provided by each layer. With this architecture we study the reflection properties of the surface and demonstrate the ability to independently tune the magnitude and the phase from the single, electrically thin surface. Tuning the magnitude and phase separately is a widely sought-after behavior and is used herein to demonstrate multiple communications modulation methods including phase-shift keying and 16-point quadrature amplitude modulation.