## 4 Simulation and Discussion
### Composite Scattering of Canyon/Valley Composite Rough Surface with Different Surface Roughness
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Figures** & **Slope Angles** & **Peak Angles** & **Peak Value (dBsm)** \\ \hline \multirow{4}{*}{(a)} & \(30^{\circ}\)–\(30^{\circ}\) & \(-30^{\circ},30^{\circ}\) & (\(74.2635\), \(81.5739\)) \\  & \(30^{\circ}\)–\(45^{\circ}\) & \(-60^{\circ},0^{\circ},30^{\circ}\) & (\(75.1674\), \(67.6920\), \(77.5633\)) \\  & \(30^{\circ}\)–\(60^{\circ}\) & \(-90^{\circ},-30^{\circ},30^{\circ}\) & (\(70.1196\), \(68.7718\), \(77.5377\)) \\  & \(45^{\circ}\)–\(45^{\circ}\) & \(-60^{\circ},30^{\circ},60^{\circ}\) & (\(75.1537\), \(77.6434\), \(72.5114\)) \\  & \(60^{\circ}\)–\(60^{\circ}\) & \(30^{\circ}\) & (\(77.8450\)) \\ \hline \multirow{4}{*}{(b)} & \(30^{\circ}\)–\(30^{\circ}\) & \(-30^{\circ},30^{\circ}\) & (\(74.2758\), \(74.1240\)) \\  & \(30^{\circ}\)–\(45^{\circ}\) & \(-60^{\circ},0^{\circ},30^{\circ}\) & (\(74.3754\), \(35.1071\), \(74.1474\)) \\  & \(30^{\circ}\)–\(60^{\circ}\) & \(-90^{\circ},-30^{\circ},30^{\circ}\) & (\(90.7841\), \(65.8235\), \(74.1959\)) \\  & \(45^{\circ}\)–\(45^{\circ}\) & \(-60^{\circ},30^{\circ},60^{\circ}\) & (\(74.3739\), \(74.1578\), \(41.8799\)) \\  & \(60^{\circ}\)–\(60^{\circ}\) & \(30^{\circ}\) & (\(73.9862\)) \\ \hline \multirow{4}{*}{(c)} & \(30^{\circ}\)–\(30^{\circ}\) & \(-30^{\circ},30^{\circ}\) & (\(74.2336\), \(96.9393\)) \\  & \(30^{\circ}\)–\(45^{\circ}\) & \(-60^{\circ},0^{\circ},30^{\circ}\) & (\(75.1781\), \(67.5802\), \(96.3810\)) \\  & \(30^{\circ}\)–\(60^{\circ}\) & \(-90^{\circ},-30^{\circ},30^{\circ}\) & (\(70.0889\), \(68.7210\), \(96.3766\)) \\  & \(45^{\circ}\)–\(45^{\circ}\) & \(-60^{\circ},30^{\circ}\), \(60^{\circ}\) & (\(75.1604\), \(96.4070\), \(81.4939\)) \\  & \(60^{\circ}\)–\(60^{\circ}\) & \(30^{\circ}\) & (\(96.4129\)) \\ \hline \multirow{4}{*}{(d)} & \(30^{\circ}\)–\(30^{\circ}\) & \(-30^{\circ},30^{\circ}\) & (\(74.3121\), \(95.7886\)) \\  & \(30^{\circ}\)–\(45^{\circ}\) & \(-60^{\circ},30^{\circ}\) & (\(74.3823\), \(95.7901\)) \\ \cline{1-1}  & \(30^{\circ}\)–\(60^{\circ}\) & \(-90^{\circ},-30^{\circ},30^{\circ}\) & (\(90.7844\), \(65.9220\), \(95.7933\)) \\ \cline{1-1}  & \(45^{\circ}\)–\(45^{\circ}\) & \(-60^{\circ},30^{\circ}\), \(60^{\circ}\) & (\(74.3808\), \(95.7944\), \(72.1102\)) \\ \cline{1-1}  & \(60^{\circ}\)–\(60^{\circ}\) & \(30^{\circ}\) & (\(95.7745\)) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Peak values of different slope-angle combinations. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Figures** & **Peak Angles** & **Peak Value (dBsm)** \\ \hline \multirow{4}{*}{(a)} & \(-30^{\circ}\) & (\(74.2836\), \(74.2807\), \(74.2795\), \(59.0459\), \(59.0324\)) \\  & \(30^{\circ}\) & (\(81.5529\), \(76.3757\), \(80.3007\), \(79.3965\), \(71.7860\)) \\ \hline \multirow{4}{*}{(b)} & \(-30^{\circ}\) & (\(74.2719\), \(74.2705\), \(74.2716\), \(58.9953\), \(58.9857\)) \\  & \(30^{\circ}\) & (\(74.0700\), \(62.5396\), \(74.0811\), \(74.0906\), \(62.6144\)) \\ \hline \multirow{4}{*}{(c)} & \(-30^{\circ}\) & (\(74.3136\), \(74.3083\), \(74.3019\), \(59.1785\), \(59.1405\)) \\  & \(30^{\circ}\) & (\(96.9244\), \(95.3232\), \(96.7281\), \(96.5997\), \(94.9308\)) \\ \hline \multirow{4}{*}{(d)} & \(-30^{\circ}\) & (\(74.2984\), \(74.2920\), \(74.2971\), \(59.1511\), \(59.1155\)) \\  & \(30^{\circ}\) & (\(95.7729\), \(94.0520\), \(95.7739\), \(95.7748\), \(94.0543\)) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Peak values of different roughness combinations. Similarly, the peak values at \(\theta_{s}=-30^{\circ}\) are mainly affected by the roughness of the right slope. Comparing the blue curve and green curve, when the roughness of the right slope increases from \(0.2\lambda\) to \(0.5\lambda\), while the roughness of the left slopes and the bottom remains unchanged, the peak value at \(\theta_{s}=-30^{\circ}\) decreases from \(74.2975\) dBm to \(59.0459\) dBm, while the peak values at \(\theta_{s}=30^{\circ}\) change less 1 dBsm. The above analysis is still valid for Figure 16b to Figure 16d.