Frequency selective absorbent structure

摘要

The structure 10 has a layered construction. It includes a conducting layer 12, a central layer 14 of thickness h and a patterned conducting layer 16 of thickness g, these layers being successively disposed. The patterned layer 16 has an array of slots such as 18. In the central layer 14, the product of propagation loss/unit length and thickness h lies in the range 0.005 to 0.1. The structure is able to absorb incident energy by means of the excitation of surface waves in the substrate layer 14. This enables the dielectric layer to be thin.