基于非均匀采样的近场散射测量技术研究  

Nonuniform Frequency Sampling Technique for Near-Field Scattering Measurements

作　　者：司炜康 王维龙[1] SI Weikang;WANG Weilong(National Institute of Metrology,Beijing 100029,China)

机构地区：[1]中国计量科学研究院,北京100029

出　　处：《计量科学与技术》2024年第8期71-77,17,共8页Metrology Science and Technology

基　　金：国家重点研发计划(2022YFF0604804)。

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。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.

关 键 词：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 

分 类 号：TB973[一般工业技术—计量学]