基于非均匀采样的近场散射测量技术研究

司炜康; 王维龙

doi:10.12338/j.issn.2096-9015.2024.0066

基于非均匀采样的近场散射测量技术研究

doi: 10.12338/j.issn.2096-9015.2024.0066

司炜康,
王维龙^,

中国计量科学研究院，北京 100029

基金项目: 国家重点研发计划（2022YFF0604804）。

详细信息

作者简介:
司炜康（1993-），中国计量科学研究院在读博士生，研究方向：电磁辐射与散射特性测量，邮箱：siwk@@nim.ac.cn

通讯作者:
王维龙（1964-），中国计量科学研究院研究员，研究方向：电磁兼容、电磁辐射与散射特性测量，邮箱：wangwl@nim.ac.cn

中图分类号: TB973
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- 被引次数: 0
出版历程
- 收稿日期: 2024-03-04
- 录用日期: 2024-03-18
- 修回日期: 2024-03-18
- 网络出版日期: 2024-05-28

Nonuniform Frequency Sampling Technique for Near-Field Scattering Measurements

SI Weikang,
WANG Weilong^,

National Institute of Metrology, Beijing 100029, China

摘要

摘要: 传统频率步进 (Stepped frequency, SF)测量体制通过一组等间隔的离散点频信号合成大测量带宽。由于采样定理的限制，固定频率间隔数据所对应的时域信号将会呈周期出现，此时场地内的背景、多径干扰都有可能混叠至目标区域内，进而对成像和散射测量造成恶劣影响。围绕频率步进体制快速测量方法进行了探索，提出了一种基于非均匀采样的近场散射测量技术。分析了距离混叠效应对散射测量的影响，根据实际应用需求设计了采样函数的优化原则，通过泊松和公式与驻定相位原理(Principle of stationary phase, POSP)对信号包络进行赋形。针对传统非均匀采样重构方法所造成的散射图像退化问题，提出了一种与非均匀采样策略相适配的加权方法，在有效抑制混叠干扰的同时实现了高分辨率成像，并提升了近远场变换(Near Field to Far Field, NF-FF)的精度。
- 计量学 /
- 距离混叠 /
- 散射测量 /
- 非均匀采样 /
- 近场成像 /
- 近远场变换
Abstract: Traditional stepped frequency (SF) systems synthesize a large measurement bandwidth using a series of equidistant discrete frequency signals. However, due to sampling theorem limitations, time-domain signals corresponding to fixed frequency intervals exhibit periodicity. Consequently, background and multipath interference in the measurement environment may alias into the target area, adversely affecting imaging and scattering measurements. This paper explores rapid measurement methods for frequency-stepped systems and proposes a near-field scattering measurement technique based on nonuniform sampling. We analyze the impact of range ambiguity on scattering measurements and design optimization principles for the sampling function based on practical application requirements. The signal envelope is shaped using Poisson's formula and the principle of stationary phase (POSP). To address scattering image degradation caused by traditional nonuniform sampling reconstruction methods, we propose a weighted method compatible with the nonuniform sampling strategy. This method effectively suppresses aliasing interference, achieves high-resolution imaging, and improves the accuracy of near-field to far-field (NF-FF) transformations.
- metrology /
- range ambiguity /
- scattering measurements /
- nonuniform sampling /
- near-field imaging /
- near-field to far-field transformation

HTML全文

图 1 均匀采样下距离混叠仿真示意

Figure 1. Illustration of range ambiguity under uniform sampling

下载: 全尺寸图片幻灯片

图 2 均匀分布、指数分布和加权平方根分布的一维距离像对比

Figure 2. Comparison of range profiles from uniform, exponential, and weighted square root frequency sampling

下载: 全尺寸图片幻灯片

图 3 指数分布、加权平方根分布和均匀分布频率采样曲线

Figure 3. Frequency sampling curves of uniform, exponential, and weighted square root frequency sampling

下载: 全尺寸图片幻灯片

图 4 数值仿真几何示意图

Figure 4. Diagram of numerical simulation

下载: 全尺寸图片幻灯片

图 5 均匀采样和非均匀采样时域图像对比

Figure 5. Comparison of time-domain images with uniform and nonuniform sampling

下载: 全尺寸图片幻灯片

图 6 均匀采样和非均匀采样成像对比

Figure 6. Comparison of uniform and nonuniform sampling imaging

下载: 全尺寸图片幻灯片

图 7 近远场变换结果对比(10 GHz)

Figure 7. Comparison of near-field to far-field transformation results (10 GHz)

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图 8 被测金属圆柱目标

Figure 8. Photo of the metal cylinder under test

下载: 全尺寸图片幻灯片

图 9 双圆柱成像结果对比

Figure 9. Comparison of imaging results of two cylinders

下载: 全尺寸图片幻灯片

表 1 三种频率分布的典型频率值(GHz)

Table 1. Typical frequency values of three frequency distributions

频率分布	n=1	n=51	n=101	n=151	n=201
均匀	10.00	11.00	12.00	13.00	14.00
指数	10.00	10.72	11.48	12.31	13.19
加权平方根	10.00	11.40	12.64	13.78	14.82
频率分布	n=251	n=301	n=351	n=401	n=451
均匀	15.00	16.00	17.00	18.00	19.00
指数	14.13	15.14	16.23	17.39	18.64
加权平方根	15.80	16.72	17.59	18.43	19.22

下载: 导出CSV

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