Double‐layer ultra‐thin artificial magnetic conductor structure for wideband radar cross‐section reduction

Abstract

A novel double‐layer chessboard‐like configuration is proposed to reduce radar cross‐section (RCS) in microwave and mm‐Wave bands. This structure is composed of two artificial magnetic conductor cells. One of these cells consists of four square patches on substrate and the other one is formed only by substrate without any copper on it. Despite the simple design of this structure, it has a big influence on significantly expanding the bandwidth of RCS reduction (RCSR). In comparison with the other works, the measured bandwidth of 10 dB RCSR is broadened to 113.33% (16.43–59.4 GHz). This wideband behaviour is achieved by effectively controlling the ratio between two dielectric constants and the ratio between their thicknesses and so the effective dielectric constant which adjusts the positions of all resonances. Although this structure contains two layers, its overall thickness is 1.4 mm, which is less than the ones that the recent works have. Measurements and simulations are performed for both monostatic and bistatic RCSs with the best number of the unit cells in the chessboard‐like structure. The design, simulations, semi‐analytical expressions and fabrication are presented and the measurements show an excellent agreement with the simulations.

Passive techniques for target radar cross section reduction: A comprehensive review

“…Ameri et al 73 designed a thin wideband RCSR surface (with a bandwidth of 109%) by two AMC cells in which the patch of AMC1 was printed on a single‐layer substrate while the patch of AMC2 was placed on a double‐layer substrate whose second layer is an air gap (shown in Figure 5C). Further bandwidth was achieved by Zaker and Sadeghzadeh 74 which is one of the widest bandwidths among the mentioned approaches in this category. They proposed a double‐layer chessboard‐like configuration by two AMC cells (shown in Figure 5d), whose 10‐dB RCSR bandwidth was broadened to 113.33%.…”

“…This approach was first investigated by Mighani and Dadashzadeh 61 by proposing a novel double‐layer chessboard surface formed by two AMC cells for RCSR with the bandwidth of 73% . Afterward, some structures with multi‐layer substrates have been proposed and achieved ultra‐wideband behavior 71‐74 . Ameri et al 73 designed a thin wideband RCSR surface (with a bandwidth of 109%) by two AMC cells in which the patch of AMC1 was printed on a single‐layer substrate while the patch of AMC2 was placed on a double‐layer substrate whose second layer is an air gap (shown in Figure 5C).…”

“…Additionally, most of them have been performed only for monostatic RCSR at normal incident angle ignoring the wave polarization. Hence, nowadays, the modern passive techniques and structures based on phase cancelation or destructive interference using surfaces including frequency selective surface (FSS), 52‐55 EM band gap (EBG), 56‐59 artificial magnetic conductor (AMC), 47,48,60‐77 polarization rotation reflective surface (PRRS), 78‐95 metasurfaces, 96‐145 and hybrid methods, 146‐149 receive a lot of attention to improve the mentioned conventional techniques and overcome their limitations. In the recent decades, researchers have made a lot of efforts on these modern passive RCSR techniques and numerous works have been proposed and completed in order to achieve a system similar to the ideal RCSR system.…”

Design of phase matching chessboard‐like electromagnetic metasurfaces for wideband radar cross section reduction

“…Similar to the design idea of Jaumann absorber, increasing the number of layers is one of the important ways to expand the operating bandwidth for the chessboard‐like AMCs structures . Certainly, the design concept of multilayers structures deviates from the development trend of “thin, light, wideband and strength” radar absorbing materials (RAMs).…”

“…Similar to the design idea of Jaumann absorber, 23 increasing the number of layers is one of the important ways to expand the operating bandwidth for the chessboard-like AMCs structures. 24,25 Certainly, the design concept of multilayers structures deviates from the development trend of "thin, light, wideband and strength" radar absorbing materials (RAMs). Therefore, to broaden the RCS reduction bandwidth without increasing the overall thickness of the structures is still an important target in the design of the chessboard-like AMCs metasurfaces.…”