A Broadband RCS Reduction Coating Using a Novel Arrangement of Metasurface Unit Cells Based on Two Substrates

Abstract

In this paper, a new coating structure is proposed for broadband radar cross section (RCS) reduction using 1-bit metasurfaces. The designed structure consists of two types of unit cell, arranged in concentric square rings. The substrate of unit cells is different, FR4 and Ultralum-2000 with thicknesses of 2.4 and 0.762 mm, respectively. The proposed structure shows an ultrawideband property to reduce the RCS, less than −10 dB, in the frequency range of 14–45 GHz. This range covers part of Ku-band (14–18 GHz), K-band (18–27 GHz), and Ka-band (27–40 GHz) and part of millimeter-wave band (40–45 GHz). To validate the designed work and simulation results, a prototype with the dimension of 84 × 84 mm² is fabricated and tested. Also, the RCS reduction is determined analytically and presented. The measured results verify well the analytical and simulation results. In short, this work includes three new points: (1) the use of two substrates with different thickness and dielectric constant to design unit cells, (2) a new arrangement of array cells in the form of concentric square rings, and (3) achieving a great bandwidth to reduce RCS.