Optically Transparent Ultra-wideband and Wide-angle Microwave Absorber By Compact Standing-Up Rounded Lattice Array

An optically transparent three-dimensional microwave metamaterial absorber based on compact standing-up rounded lattice array is presented. The absorber has ultra-wideband, wide-angle absorption and polarization-independent properties. Our theoretical investigations and simulations demonstrated that the compact standing-up resistive patch arrays can not only excite multiple standing wave modes to obtain ultra-wideband absorption, but also enhance the absorption bandwidth progressively with the increase of the incident angle for the oblique transverse magnetic. Both the simulations and the measurements indicate that the proposed absorber can achieve ultra-wideband microwave absorption with efficiency over 90% and 95% in the frequency band of 3.5-31.8 GHz (fractional bandwidth, FBW=160%) and 4-31GHz (FBW=154%), respectively.