基于稀疏采样与级联字典的微波辐射图像重构方法*

针对微波辐射测量成像系统在一次观测中所采集的数据量大,基于奈奎斯特采样的常规,微波辐射成像方法难以实现高分辨率要求。本文在挖掘微波辐射图像多结构信息可压缩的基础上,利用随机观测矩阵对微波辐射图像进行线性压缩投影,减少数据采集量,降低系统的复杂性。考虑微波辐射图像具有多结构形式,采用单一的正交基难以稀疏表示复杂场景的微波辐射图像,利用全变差分和小波的级联字典对微波辐射图像进行稀疏表示,然后用OMP 算法重构微波辐射图像。仿真实验结果表明:级联字典重构微波辐射图像的性能优于单一正交基。     

Application of the thermoelectric MEMS microwave power sensor in a powerradiation monitoring system

A power radiation monitoring system based on thermoelectric MEMS microwave power sensors is studied. This monitoring system consists of three modules: a data acquisition module, a data processing and display module, and a data sharing module. It can detect the power radiation in the environment and the date information can be processed and shared. The measured results show that the thermoelectric MEMS microwave power sensor and the power radiation monitoring system both have a relatively good linearity. The sensitivity of the thermoelectric MEMS microwave power sensor is about 0.101 mV/mW, and the sensitivity of the monitoring system is about 0.038 V/mW. The voltage gain of the monitoring system is about 380 times, which is relatively consistent with the theoretical value. In addition, the low-frequency and low-power module in the monitoring system is adopted in order to reduce the electromagnetic pollution and the power consumption, and this work will extend the application of the thermoelectric MEMS microwave power sensor in more areas.     

单脉冲微波功率与能量的量测

讨论了应用电磁波的辐射压力在空间测量微波功率，特别是单次脉冲高功率微波的峰值功率和能量的方法。设计了一个测量空间辐射压力的悬挂系统扭秤。对于该悬挂系统进行了系统模拟，给出了测量微波辐射压力的定性实验结果。证明该方法是可行的。     

Microwave-transmission, heat and temperature properties of electrically conductive adhesive

Microwave heating significantly speeds up the curing process of polymer and polymer-based composites. The present theoretical work studies the microwave transmission through the electrically conductive adhesive (ECA), heat generation and transfer inside the ECA and subsequently the microwave heating rate of the ECA. By studying the temporal transmission property of the microwaves in the ECA, we have calculated quantitatively the electromagnetic field distribution around a metal filler. It has been shown that the penetration depth of the skin effect in the metal filler is significantly smaller than the one of a bulk metal material. The heat generation (microwave power absorption) is negligible in the metal filler due to its large electric conductivity. Furthermore, due to the high thermal conductivity, the thermal equilibrium between the metal filler and the surrounding adhesive is reached within a nano second (10/sup -9/ s). The temperature of the whole ECA system becomes uniform within a time interval of 10/sup -3/ s. When the temperature of the system is relatively low, the heating rate of the system is linearly proportional to the external microwave input power and the heating time. It gradually saturates when the temperature of the ECA is so high that the heat radiation from the ECA becomes significant. Numerical results of our theoretical model agree well with experimental data, thus providing a solid platform for designing the microwave curing process of the ECA.     

一种载波对消提高相位调制度的新技术

用连续波雷达测量运动目标或振动目标经常会遇到调相波的解调问题。对于无外向辐射的封闭系统,结合微波马赫-曾德尔干涉仪和灵敏高效的相位调制器,设计了一种简洁有效的技术架构,实现了载波对消。高效相位调制器提高了对振动的响应,干涉仪不但可以有效压制载波,而且极大压制了微波源的相位噪声,包括难以处理的1/ f 噪声。该技术适用于各种频段,可有效延伸到射频,用集中参数系统处理,这样,更加有利于调相传感器的优化和电路实现。文中给出了高效相位调制器和干涉仪系统的原理分析,验证方案和同轴系统的实验结果。该原理也适用于微带电路和集成化电路。     

Magnetic-field controlled resonances in a gapped-post-adjacent-plunger system

It is found that, in a gapped-post-adjacent-plunger system, reflection of microwave radiation occurs. This reflection is dependent on the magnitude and direction of the magnetic field. It is indicated that this phenomenon can be used for the development of tunable microwave cavities.     

A system for studying effects of microwaves on cells in culture.

An improved design of the fluid-filled waveguide-exposure chamber is described for studying effects of microwave radiation on cells in vitro. The system with a micropipette sample holder may be used as a prototype to isolate the apparent nonthermal factor of microwave radiation on cells in culture from those effects resulting from cell temperature rise. This system also allows more precise calibration of incident and absorbed microwave energies. Compared with control, somatic cells of the Chinese hamster exhibited a lower rate of growth and difference in morphology after 2450 MHz microwave radiation for 20 min at a power density of 500 mW/cm2.     

微波功率管测量的微波辐射分析与防护

该文介绍了微波辐射防护的理论知识和安全标准,以及微波功率管测量系统的配置和测量流程。对测量系统的微波电磁辐射进行了分析,列举了在微波功率管测试工作中采取的一些防护措施和测评结果,阐述了使用程控化测量系统对微波辐射防护的益处。     

基于光学技术的太赫兹相干辐射源研究

由于太赫兹辐射的独特性质和潜在的应用价值, 国内外关于太赫兹波的产生和探测的研究正呈现日益繁荣的景象, 目前太赫兹相干辐射源的研究已成为太赫兹技术领域最重要的前沿课题之一。介绍了产生太赫兹相干辐射的三种主要途径：一是光学技术, 它从高频向低频发展, 其代表为太赫兹激光器, 如气体激光器、半导体激光器和量子级联激光器等; 二是电子学技术, 它由低频向高频发展, 如微波管、固体微波源等; 三是光电子技术, 其频率由1 THz向两侧展宽, 采用超快激光脉冲触发产生太赫兹脉冲。设计了基于光学技术的太赫兹相干辐射系统, 该装置根据气体振转能级跃迁原理, 采用高压直流激励方式产生受激辐射, 波导管谐振腔体, 工作气体为N2, CD4和D2, 经过优化设计, 预计可以产生1.54 THz和1.58 THz的波连续输出。     

基于混合稀疏基字典学习的微波辐射图像重构方法

目前的微波辐射测量成像系统在一次观测中所采集的数据量大,基于奈奎斯特空间采样及常规微波辐射图像重构方法难以实现高分辨率要求。该文针对微波辐射干涉测量在频域中进行,采用傅里叶最优随机抽取的超稀疏干涉测量(低于奈奎斯特采样)对微波辐射图像进行线性压缩投影,降低数据采样。考虑微波辐射图像在总体差分域和小波中都具有可压缩特性,提出总体差分和小波混合正交基的K-SVD字典学习微波辐射图像重构模型,利用Bregman和交替迭代算法求解该模型,重构线性压缩投影信息从而获得微波辐射图像。仿真实验表明,该文提出的算法在微波辐射图像重构效果、噪声稳定性上优于DLMRI算法和GradDLRec算法。     

一种双频微波功率合成器的设计与实现

一种新型的双频微波功率合成器，通过阶跃阻抗低通滤波器和平行耦合线带通滤波器构成的微带电路实现。该微波功率合成器实现了915MHz和2．5GHz两个非相干频率微波信号的功率合成。同时通过附加工作在915MHz和2．5GHz的20dB微带定向耦合器，就可以构建实验系统进行微波功率合成的测量。实验测量结果与数值模拟结果吻合，双频微波功率合成器和定向耦合器的性能达到了要求，可用于注入式微波器件效应的研究。     

The relation of sex, age, and weight of mice to microwave radiation sensitivity.

It is of interest to determine whether the weanling mouse, the sexually mature mouse, or the aged mouse of both sexes are similarly sensitive to microwave radiation. This study included 114 male and female mice irradiated to death with 2450 MHZ microwave radiation at 7.5 watts forward power, a minimum of 14 mice being used for any single set of variables. Weanling mice of 1 month of age are fully developed with respect to most organ systems except the reproductive. Two month old mice are sexually and otherwise mature, fully capable of survival and reproduction. The age mice of both sexes were ex-breeders which had been used for constant litter production for at least 12 months, and had waning reproductive potential. They were therefore about 14 months of age. It was found that the male mice on the average weighed more than the females (least difference at weaning) and both showed considerable weight increase with age; that weanling males irradiated to death absorbed slightly more radiant energy than did the weanling females, but they were also slightly heavier; that time to death under constant exposure from the beam increased with age for both sexes, indicating increasing microwave resistance with age and/or weight; that the mean absorbed dose at death did not show significant differences related to age or weight within the same sex; that the males showed slight increase in radio-tolerance with age and/or weight as measured by the absorbed dose at death when compared with the females which showed a decline in radio-tolerance with age and/or weight; that in all cases sex seemed to be somewhat more important than did age or weight in determining the lethal absorbed dose at death; and that it took longer longer for the older mice to die due probably to the fact that the rate of absorption of radiation was slower with their increased weight. It is the absorbed dose in joules per gram that is biologically significant and the data shows that the mean absorbed dose to death within either sex shows no significant difference with respect to age or weight, but that the difference between the sexes are significant, particularly among the aged ex-breeders.     

Frequency-selective surface for microwave power transmission

Using an equivalent-circuit model, frequency-selective surfaces (FSS's) with gridded- and double-square elements have been designed and tested for suppressing the harmonics radiation in microwave power transmission system. It is shown that the angular sensitivity of the frequency response of the FSS arrays can be reduced with a combination of TE- and TM-polarized incident waves or a circularly polarized incident waves instead of a single TE- or TM-polarized incident wave. The FSS arrays have also been measured in a microwave anechoic chamber and a good agreement is obtained between the theoretical calculations and experimental results     

Cataracts and cell-phone radiation

A concern that is often expressed about microwave radiation is the induction of cataracts. The formation of lens opacities in the eyes of laboratory animals following acute microwave exposure is well established. It is generally accepted that acute exposure to higher levels of CW radiation causes various degrees of lens opacification in laboratory animals at many microwave frequencies. However, the exact conditions under which these changes may occur in human beings are a subject of debate. Nevertheless, linear extrapolations of computed results indicate that the incident density required for the human eye to reach the cataractogenic threshold may only be slightly lower than that needed for rabbits.     

无源微波遥感用于地震预报的实验研究

对无源微波遥感用于地震预报在理论研究的基础上对不同岩性不同结构的岩石试件进行了加载实验，测量了岩石试件的微波辐射随载荷的变化．实验得出：岩石试件的微波辐射能量随岩石应力状态变化而显著变化；而且，不同的波段变化的幅度不同；同一波段不同极化方式的波随应力变化的变化量也不同；微波辐射能量的变化能够被卫星微波遥感探测器探测到．实验还发现，岩石试件临破裂前出现明显的微波辐射异常．     

微波辐射峰值吸收频率对原油组分的影响

利用微波辐射降低原油粘度是一种新的高效处理方法,微波降粘效果取决于油样吸收微波的能量,油样对微波的吸收率取决于微波频率,因此油样最大能量吸收率所对应的微波频率定义为峰值吸收频率。基于微波二端口网络模型,利用自行设计的微波辐射实验设备进行研究,精确测量了待测油样的峰值吸收频率,并详细分析了频率对原油组分的影响。结果表明:在3.9 ~6.5 GHz 的扫描频率下,油样在频率为5.8 GHz 时出现第1个吸收频率且能量仅剩69.9%,在6.2 GHz 时出现第2 个吸收频率且能量仅剩36.4%,该频率为峰值吸收频率;运用GCMS分析经过5.8 GHz 和6.2 GHz 微波辐射后,轻组分(C7-C14)分别增加了7.6%、8.7%,重组分(C16 及以上碳数)分别减少12.4%、13.5%,原油组分发生明显的改变。研究结论为微波辐射技术在石油行业运用提供了重要的参考,证明了该技术具有良好的应用前景。     

微波辐射Fenton试剂氧化催化降解水中三氯乙烯

对微波辐射与Fenton试剂氧化催化法相结合降解水中三氯乙烯进行了研究。采用单因子法考察了反应时间、Fenton试剂用量和配比、反应物初始浓度、PH值，微波功率和压强等条件对脱氯率的影响。结果表明，三氯乙烯脱氯率随微波功率，压强、反应时间的增加而增加，随以应物初始浓度的增加而降低。Fenton试剂用量，比例和反应物初始Ph有一个最佳值。采用正交试验法对影响脱氯降解作用明显的催化剂量、Fenton试剂配比，反应时间，微波功率进行了优化分析，结果表明，在Fenton试剂摩尔比为60，Fenton试剂用量10%，反应时间12min、微波功率750W的最佳条件下，三氯乙烯脱氯率可以达到87.08%。     

对地观测的微波散射成像方法

以微波为探测手段进行对地成像观测,能够全天候、全天时工作,在许多技术领域得到了重要应用,对微波成像的新思想、新体制、新技术的探索,也是一个非常活跃的研究领域。该文提出了一种新的微波成像方法,称为微波散射成像方法,该方法可采用收发分置工作方式,工作时只需要以单色波照射待成像地域。原理性成像模拟结果表明,使用这种方法可以获得被观测地域高几何分辨率和高辐射分辨率的微波图像。     

微波辐射对不同植物油温度响应规律影响的研究

本文探讨不同微波参数下植物油的温度响应规律变化情况。研究结果表明，微波平均辐射强度对植物没的温升曲线及其线性相关性影响较大。为此，建立了描述不同微波辐射强度下有关植物油温度与时间关系的数学模型，并分析了微波辐射对金属温度传感器的测温原理。