# Dual-Polarization Conversion and Coding Metasurface for Wideband Radar Cross-Section Reduction
## 5 Configuration and Analysis of RCS Reduction with Coding Metasurface
Figure 8 depicts the configuration of the proposed 1-bit CM. The structure is composed of 6 \(\times\) 6 lattices, with 5 \(\times\) 5 same meta-atoms on each lattice. The coding metasurface \"0\" and \"1\" patterns have scattering phases of 0\({}^{\circ}\) and 180\({}^{\circ}\), respectively. In similar ways, the vertical and horizontal coding sequences are realized. Figure 7: Layout of meta-atom: (**a**) ‘1’ element, (**b**) ‘0’ element, and (**c**) reflection phases of ‘1’ and ‘0’ with their phase difference. _RCS Reduction of Planar Coding Metasurface_  
Figure 8 depicts a planar MS array with 30 \(\times\) 30-unit cells to verify the performance of a proposed metasurface. The properties of RCS reduction are evaluated by simulating the proposed coding metasurface in the time domain using CST Microwave Studio. All boundaries during the simulation are configured to open add-space. Perhaps a plane wave is an incident along the negative z-axis at a distance of \(\lambda\)/4 from the MS. A metallic plate of the same size as the reference is employed for the investigations. The monostatic RCS results of a composed 1-bit CM with a planar metallic slab of identical size under a normal incidence \(y\)-polarized wave are shown in Figure 9a. It is worth noting that the proposed coding metasurface effectively achieves more than 10 dB of radar cross-section reduction in the frequency range of 13.1-13.8 GHz and 20.4-30.9 GHz, with a maximum radar cross-section reduction value of 28 dB. The frequency ranges that the RCS decreases roughly correspond to those of meta-atoms '0' and '1', where the PCR is higher. A maximum radar cross-section reduction is also observed in the frequency range of 13.1-13.8 GHz and 20.4-30.9 GHz, according to proper polarization conversion ratio conditions. Moreover, we investigate the normalized monostatic RCS reduction for different polarization states, as shown in Figure 9b. The designed structure has the same response for all polarization states, indicating that it is polarization-insensitive, which is essential for practical applications. To learn more about the radar cross-section reduction technique, the far-field of the proposed 1-bit CM is simulated at 12.64, 23.32, and 26.06 GHz on the same scale as a metallic plate of the same size. Figure 10 shows the three-dimensional (3D) far-field scattering patterns under normal incidence. Figure 8: Configuration of 1-bit coding metasurface (CM) with 5 \(\times\) 5 meta-atoms of ‘1’ and ‘0’. Figure 10d-f show the field distribution of a metallic plate at 12.64, 23.32, and 26.06 GHz, while Figure 10a-c show the field distribution of a 1-bit CM at the same frequency. The metallic plate exhibits a significant reflection lobe in the direction of the incident when electromagnetic waves impinge on it, while the coding metasurface exhibits a distribution of incident EM waves in all four directions due to destructive interference between lattices '0' and '1'. Consequently, the direction of incidence will realize minimal reflection, leading to a significant decrease in the resultant radar cross-section. Nevertheless, the primary lobe in Figure 10a comprises the majority of the energy, which will reduce scattering performance at the central frequency. Due to its polarization-independent characteristics, the metasurface only considers the reduction in radar cross-section within various incident angles for the \(y\)-polarization direction. Figure 11 provides information on the performance of simulated radar cross-section reduction at various incident angles (\(\theta=0^{\circ},10^{\circ},20^{\circ},30^{\circ}\), and \(40^{\circ}\)). Figure 11 shows the CM model's RCS reduction performance  
Figure 10: Three-dimensional scattering performance of (**a–c**) coding metasurface and (**d–f**) PEC under normal incident x-polarized wave at 12.64, 23.32 GHz, and 26.06 GHz. Figure 9: (**a**) Monostatic RCS reduction of PEC and MS under a normal \(x\)-polarized wave, and (**b**) RCS reduction in different polarization states.