A Reflecting/Absorbing Dual-Mode Textile Metasurface Design

A textile-based reflecting/absorbing dual-mode metasurface is proposed in this paper. For the reflecting mode of the design, a conventional square patch electromagnetic band gap (EBG) structure is adopted and the zero-degree refection phase center is tuned to 2.4 GHz. For the absorbing mode, a carbon-coated resistive net is applied on top of the EBG patches to redirect the current flow at resonance and hence achieve energy dissipation with the resistance. The underlying reconfigurable logic is analyzed with a dispersion diagram, surface current distribution, and equivalent circuit/impedance matching analysis. By applying a state-of-the-art AI-driven antenna design technique, self-adaptive Bayesian neural network surrogate model-assisted differential evolution for antenna optimization (SB-SADEA) method, the geometry parameters can be accurately determined meanwhile maintaining absorption and reflection band of the design centered at the same frequency. The fabricated prototype of the design can achieve a maximal absorption of 99.8% (-29.2 dB) and maintain an absorption over 90% in the frequency range of 2.39 to 2.42 GHz. To verify the reflection properties, a textile monopole antenna was fabricated and tested along with the reflection metasurface. A 5-dB realized gain enhancement can be achieved at 2.4 GHz with the applied metasurface. Both simulations and measurements verify the effectiveness of the proposed dual-mode metasurface design.