A Gravity Tailored Ultra-broadband Absorber Based on High-impedance Surface

We design a three-dimensional ultra-broadband tunable metamaterial absorber tailed by the gravity field (GF) with changing the position of the liquid metal in theory. The ultra-broadband absorption is achieved by the high-impedance surface and the liquid metal. Furthermore, the tuning absorption can be implemented by virtue of the liquid metal pouring into the different parts of the glass cavities under GF regulation. When such an absorber is not rotated, for the TE wave, the absorption rate exceeds 90% at 1.8–57.5GHz with a wide relative absorption bandwidth of 187.8%. yet for the TM wave, the absorptivity goes beyond 90% from 5.6 GHz to 56.4 GHz. The presented absorber exhibits ultra-broadband absorption at 1.6–45.3GHz (the absorptivity is higher than 90%) with this absorber rotated 180° in the x-y plane for the TE and TM waves. While the absorptivity is near to null at 1.6 60 GHz with the devised absorber rotated 180° in the y-z plane. Besides, the simulations show that this absorber can realize the high absorption upon a wider incident angle.