## 2 Coding Metamaterials for RCS Reduction
### Coding Metamaterial Parametric Study
#### 2.3.4 Twelve Lattices  
The 12 lattices exhibited the second-best and unique results in this parametric study. Overall, all the coding sequences successfully produced monostatic RCS values that reached almost \(0\) dBm\({}^{2}\) at the Ku-band, as shown in Figure 9. Meanwhile, at the C-band, RCS values ranging from \(-20\) dBm\({}^{2}\) to \(-9\) dBm\({}^{2}\) occurred for all the metamaterial sequence designs. However, the bistatic scattering patterns of the three coding sequences differed from each other. Moreover, the peak value of bistatic RCS reached a \(-8.3\) dBm\({}^{2}\) for Coding Sequence 3. A comparison of the coding sequences in the 6 and 12 lattices revealed tremendous changes in the monostatic RCS values. Therefore, for one-bit coding metamaterials, a larger design structure is required to gain the highest RCS reduction values. The arrangement of elements '0' and '1' for the 12 lattices is illustrated in Table 9.  
Figure 8: Monostatic RCS and bistatic scattering patterns (at 8 GHz) of three different coding metamaterials with eight lattices.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Coding Sequence** & **1** & **2** & **3** \\ \hline Row 1 & 11011011 & 10011011 & 10010001 \\ Row 2 & 10100101 & 11011011 & 00101010 \\ Row 3 & 01010100 & 01010100 & 01010100 \\ Row 4 & 10001010 & 10101001 & 10101001 \\ Row 5 & 01001010 & 01101001 & 01011010 \\ Row 6 & 00110101 & 00110101 & 10101001 \\ Row 7 & 01001010 & 01001010 & 01010010 \\ Row 8 & 01010101 & 11100111 & 10100101 \\ \hline \hline \end{tabular}
\end{table}
Table 8: Coding sequences of \(n=8\) for each row.  
Figure 11: Monostatic RCS and bistatic scattering patterns at 8 GHz for three different coding metamaterials with 20 lattices.  
Figure 10: Coding metamaterial designs for 20 lattices: (**a**) Coding Sequence 1; (**b**) Coding Sequence 2; and (**c**) Coding Sequence 3.  
Overall, five lattices revealed promising outcomes, and the monostatic RCS values were tremendously reduced for the larger coding metamaterial design. As mentioned earlier, the one-bit coding metamaterial design utilised only the '0' and '1' elements and arrange distinct in dimensions based on the number of lattices. Therefore, initially, a smaller number of lattices (four) was adopted to analyse the performance changes in RCS values. Moreover, the first three numbers of lattices increased by two, while the following numbers of lattices increased by four and eight, respectively. The changes in the monostatic RCS values from 6 to 12 lattices manifested the first tremendous outcomes and thus revealed better results compared to the previous numbers of lattices. However, the 20-lattice coding metamaterial designs exhibited extraordinary RCS reduction values, even enabling positive values. The monostatic RCS values almost reached 6.5 dBm\({}^{2}\) with the 20-lattice coding metamaterial designs. Thus, the coding metamaterial enabled unique properties by simply arranging the selected elements based on the desired dimension and controlling scattering patterns, but for optimized RCS-reduction values, a larger one-bit coding metamaterial is required.