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摘要:
用缩比模型测量结果预估是研制阶段获得大尺寸目标雷达散射截面(RCS)的常用方法,但根据经典电磁相似理论,严格满足缩比条件的涂覆吸波材料缩比目标测量难以实现。针对涂覆吸波材料缩比目标的RCS预估问题,提出了采用多元对数线性回归模型的预估方法。设计了2组圆柱模型,在微波暗室中对缩比因子分别为1、2、4、8的2组模型进行了测试。在完成角度矫正等数据预处理基础上,将缩比模型RCS数据作为训练集代入模型当中求得参数,对原模型的RCS进行预估并与实际实测数据进行对比分析。结果表明:所提方法预估数据与实测数据曲线拟合度较好,相较于传统平方率模型,误差下降了3~5 dB,在回归模型中加入吸波材料因子后误差进一步下降了0.3~0.8 dB。
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关键词:
- 雷达散射截面(RCS) /
- 缩比模型 /
- 多元线性回归 /
- 吸波材料 /
- 相似原理
Abstract:Large target's Radar Cross Section (RCS) estimation using scaling model is a common method to obtain RCS at the development phase. However, according to classical electromagnetic similarity theory, measurement of scaled target coated with microwave absorbing material is difficult to meet the scaling condition strictly. A multivariate logarithmic linear regression model is proposed to estimate RCS for the scaled target coated with microwave absorbing materials. Two sets of cylindrical models were designed and tested in the microwave anechoic chamber with scaling factors of 1:1, 1:2, 1:4 and 1:8, respectively. On the basis of data preprocessing such as angle correction, RCS data of scaling model is substituted into the model as training set to obtain parameters, and RCS of the original model is estimated and compared with the actual measured data. The results show that the curves of the predicted data and the measured data fit well. Compared with the traditional square rate formula, the error of the proposed method decreases by 3-5 dB, and the error decreases by 0.3-0.8 dB after adding the microwave absorbing material factor to the regression model.
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表 1 电磁相似原理条件
Table 1. Conditions of electromagnetic similarity principle
物理量 原模型 缩比模型 长度 l l′=l/n 频率 f f′=nf 波长 λ λ′=λ/n 电导率 σ σ′=nσ 磁导率 μ μ′=μ 介电常数 ε ε′=ε 表面阻抗 η η′=η 表 2 圆柱1的尺寸及测试频率
Table 2. Dimension and test frequency of cylinder 1
n 长度/mm 直径/mm 测试频率/GHz 组数 0.96 2 092 159 1.5~2 101 2 1 000 76 3.5~4.5 201 4 500 38 7~9 401 8 250 19 14~18 801 表 3 圆柱2的尺寸及测试频率
Table 3. Dimension and test frequency of cylinder 2
n 长度/mm 直径/mm 测试频率/GHz 组数 1 480.0 240 2~2.5 101 2 240 120 3.5~4.5 201 4 120 60 7~9 401 8 60 30 14~18 801 表 4 测量误差与目标和背景电平的差值典型数据
Table 4. Typical data of measurement error according to difference of target and background ratio
测量误差/dB 31 ±0.25 25 ±0.5 19 ±1 16 ±1.5 10.69 ±3 表 5 圆柱1数据角度校准结果
Table 5. Calibration results of angle of cylinder 1
(°) 极化方式 n=0.96 n=2 n=4 n=8 HH -0.6 0.2 -0.2 -0.2 VV -0.6 0 -0.2 0.4 表 6 圆柱2数据角度校准结果
Table 6. Calibration results of angle of cylinder 2
(°) 极化方式 n=1 n=2 n=4 n=8 HH 0.2 0.2 0.2 0.8 VV 0 0.2 0.4 -0.2 表 7 圆柱1的模型1摘要(HH极化)
Table 7. Model one's summary of cylinder 1(HH polarization)
R R2 调整后的R2 标准估算的误差 0.980 0.961 0.961 1.602 808 表 8 圆柱1的模型1回归方程系数(HH极化)
Table 8. Model one's regression equation coefficients of cylinder 1 (HH polarization)
因子 系数 标准错误 t 显著性 x1 0.943 0 2 830.873 0 x2 27.175 0.041 967.286 0 表 9 圆柱1不同模型回归公式与平均绝对误差对比
Table 9. Comparison of regression formula and absolute error of cylinder 1 in different models
极化方式 模型 回归公式 相关系数 拟合度 平均绝对误差/dB HH极化 传统平方率模型 y=x1+20x2 0.927 0.859 4.93 HH极化 模型1 y=0.943x1+27.175x2 0.980 0.961 1.94 HH极化 模型2 y=0.996x1+21.279x2-0.08x3-0.708x4 0.998 0.995 1.11 VV极化 传统平方率模型 y=x1+20x2 0.934 0.872 5.26 VV极化 模型1 y=0.991x1+30.630x2 0.992 0.984 2.14 VV极化 模型2 y=1.039x1+19.476x2-1.728x3-0.378x4 0.994 0.988 1.29 表 10 圆柱2不同模型回归公式与平均绝对误差对比
Table 10. Comparison of regression formula and absolute error of cylinder 2 in different models
极化方式 模型 回归公式 相关系数 拟合度 平均绝对误差/dB HH极化 传统平方率模型 y=x1+20x2 0.934 0.872 7.18 HH极化 模型1 y=0.969x1+33.130x2 0.996 0.992 2.30 HH极化 模型2 y=0.964x1+26.455x2+0.355x3-0.483x4 0.997 0.995 1.62 VV极化 传统平方率模型 y=x1+20x2 0.946 0.895 5.92 VV极化 模型1 y=1.005x1+30.119x2 0.989 0.979 2.41 VV极化 模型2 y=0.969x1+19.469x2+0.046x3-0.894x4 0.991 0.982 2.18 -
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