Design of Wideband Metasurface Structure with the Aid of Bottom-Up Optimization

This paper presents a design methodology leading to optimize an electromagnetic metasurface structure usable in a wide band frequency. The structure consists of identical unit cells realized in microstrip technology, being one of them fed by a coaxial cable. The employed approach is the bottomup optimization (BUO) that is implemented by increasing the number of radiators following a squared scheme of $n \times n$ nature. The proposed methodology leads to design optimal complex structures exhibiting a wideband feature. For validating the use of BUO method, the number of radiators has been increased from 1 to 25, i.e., n has been varied form $n=1$, to $n=5$. The initial design parameters of antennas are obtained through particle swarm optimization (PSO) algorithm. The simulation results show that the optimized metasurface with the aid of BUO method has a wideband frequency answer in the range from 13 GHz to 22.66 GHz.