A Novel High Suppression Multilayer Frequency-Selective Surface Based on Hexagonal Grids

Abstract

This paper addresses the issue of achieving excellent overall performance for frequency selective surface (FSS) radomes. A dual-layer frequency selective surface based on a hexagonal structure is proposed, which offers broadband suppression, roll-off characteristics, angular stability and a low insertion loss passband. The proposed FSS unit consists of two dielectric layers and a PMI foam layer, with conductive layers placed on both sides of the PMI foam. The FSS is composed of hexagonal ring units and three-level sub-centre units. This design achieves broadband suppression from 2 to 20 GHz, while maintaining a flat passband between 7.59 and 8.71 GHz, corresponding to a relative bandwidth of 10.8%. The transmission characteristics remain stable with incident angles ranging from 0° to 50° under both TE and TM modes. To validate the feasibility of the FSS design, a physical prototype was fabricated and tested. The experimental results show that the FSS performs well in broadband suppression, roll-off characteristics, flat passband and angular stability, in agreement with the simulation results. This demonstrates its strong overall performance and promising potential for applications in stealth antenna radomes.