双频微波辐射计的温度控制电路

双频微波辐射计这种被动式遥感仪器可同时独立地测量大气对流层中的水汽和液态水含量,它主要包括天线及控制系统、接收机、数据预处理和主计算机四个部分。整个辐射计的接收机组件和有关电路都置于恒温机箱中并配以高精度温控电路,使参考负载的温度保持不变。这套恒温装置可以保证在环境温度从-20℃到+50℃范围内变化时,箱内的温度保持     

数字增益自动补偿微波辐射计的计算机仿真

数字增益和补偿微波辐射计是一种新型的微波辐射计,它能很好地实现增益补偿,有效地提高微波辐射计性能,更适合星载使用,本文对以全功率微波辐射计为基础的数字增益自动２微波辐射计进行仿真,分析了全功率微波辐射计的特点,并在此荐 ,提出了在频程跨度很大时实现系统频域仿真的有效方法,仿真结果不仅证明功率微波辐射计的特点,在此基础上,提出了在频程跨度很大时实现系统频域仿真的有效方法,仿真的结果不仅证明所采用的方     

星载合成孔径微波辐射计的反演公式

本文利用相关理论对星载合成孔径微波辐射计（简称SAMR）进行了详细的分析和探讨，给出它对地物辐射响应的一般表达式。当地物辐射源为非相关时，得到窄带SAMR对地物亮温度分布的反演公式。当地物辐射源为相关时，论述了辐射计的输出不含地物亮温度分布有用信息。     

微波辐射计的SIR图像重建算法

提出了图像重建可以提高微波辐射计分辨率,并对图像重建的SIR算法原理进行了研究;从采样间隔和迭代次数两方面分别对图像含噪声和不含噪声两种情况进行仿真验证.结果表明,SIR算法是一种有效的图像重建算法.     

地空路径水凝物交叉极化特性研究

水凝物的交叉极化预报模式对10GHz以上频段使用正交极化频率复用的卫星通信系统设计具有重要意义.基于ITU-R与OPEX数据库的地空雨致交叉极化数据和二阶小变量近似的预报模式,给出了一种改进的雨致交叉极化预报模式.与其它模式比较表明,这一模式的预测精度有明显提高.     

微波辐射计的功率非线性对标定天线温度的影响

微波辐射计通过两点定标反演天线温度依赖的是辐射计的输入功率与输出电压的线性关系。通过分析平方律检波器的输入功率与输出电压的关系，导出非线性系数与由口面定标法反演的天线温度误差的关系式。定量说明了功率非线性度引入误差的大小．通过计算分析得出两种定标系统（地面遥感和星载遥感）对功率非线性度的要求。     

基于地基微波辐射计的大气参数廓线遥感探测

介绍了实时连续遥感探测大气温度廓线、湿度廓线和液态水含量廓线的地基微波辐射计。通过无线电气球探空测量的温度、湿度廓线、太阳辐射计测量的晴天水汽总量与微波辐射计探测结果的对比,证明该微波辐射计可以可靠地探测大气温度、湿度和水汽总量。通过对两个典型天气事件微波辐射计的观测数据分析表明：微波辐射计还可以监测云和天气变化的过程信息。     

基于数字相关型全极化微波辐射计的灵敏度分析

灵敏度是表征微波辐射计能够检测到最小亮温变化的能力,是微波辐射计一项重要指标.本文针对数字相关型全极化微波辐射计,提出了一种使用相关器输出的计数值计算各通道灵敏度的方法,并通过了实验验证.对比模拟通道灵敏度和数字通道灵敏度,分析了量化噪声和通道间串扰对灵敏度的影响.     

联合星载毫米波雷达和激光雷达资料的云相态识别技术

依据星载偏振激光雷达云相态识别原理,借鉴星载毫米波雷达温度阈值云相态识别方法,利用支持向量机(SVM)构建了联合CloudSat和CALIPSO卫星资料的云相态识别模型并进行了实例反演验证.SVM方法训练和测试样本集采用了CloudSat的2B-GEOPROF-LIDAR云廓线数据、CALIPSO的2级1km云层数据以...     

雷达辐射对微波业务的干扰

从雷达发射向多样化发展的趋势和目前雷达工作特点、辐射特性几方面阐述了雷达对微波通讯的干扰机理、途径。     

Mapping the atmospheric water vapor by integrating microwave radiometer and GPS measurements

This paper deals with a procedure to generate maps of the integrated precipitable water vapor (IPWV) over the Mediterranean area by using estimates from a global positioning system (GPS) network over land and from the Special Sensor Microwave/Imager (SSM/I) over sea. In particular, we investigate the application of the kriging geostatistical technique to obtain regularly spaced IPWV values. The horizontal spatial structure of water vapor retrieved by SSM/I is explored by computing variograms that provide a measure of dissimilarity between pairs of IPWV values for the region of interest. Because the water vapor density decreases with height, the GPS station elevation is accounted for in the interpolation procedure. In this respect, the potential of the kriging with external drift relative to the ordinary kriging is evaluated by applying a test based on the cross-validation approach. Case studies are presented and qualitatively compared to the corresponding Meteosat infrared images. A quantitative comparison with an independent source of information, such as IPWV computed from radiosonde observations and from European Centre for Medium-Range Weather Forecasts analysis, is also performed.     

微波辐射计在雷测数据折射误差修正中的应用

基于用微波辐射计实时测量反演大气折射率剖面的研究,并与施放气象探空仪直接测量的结果进行比对,结果表明微波辐射计实时测量反演得到的大气折射率剖面能够较好地反映雷达站所在地的折射率分布。将反演和实测折射率剖面应用于某次雷达测量数据的电波折射误差计算中,由修正量比对残差分析结果得出:将微波辐射计实时测量反演的大气折射率剖面用于电波折射误差修正是有效的。为微波辐射计应用于高精度机动测控雷达,提高测量数据处理的精度提供了理论和试验依据。     

Discrete scatter model for microwave radar and radiometer responseto corn: comparison of theory and data

As part of the Multisensor Aircraft Campaign, MACHYDRO, two microwave sensors, NASA's Airborne Synthetic Aperture Radar (AIRSAR) and Pushbroom Microwave Radiometer (PBMR) collected data over the same corn fields during the summer of 1990. During these flights, measurements were made on the ground of soil moisture and plant parameters. In this paper the measured canopy and soil parameters are used in a discrete scatter model to predict the response of both sensors (radar and radiometer). A distorted Born approximation is used to compute the scattering coefficient for the corn canopy. The backscatter coefficient gives the radar response and the radiometer response is obtained by integrating the bistatic coefficient over all scattering angles above ground. The objective of this analysis is to test the model and, in particular, to determine how well a single set of plant parameters and single model can yield agreement with both the radar and radiometer measurements. The model values are in reasonably good agreement with the measurements at horizontal polarization and reflect observed changes in soil moisture     

微波辐射计探测大气剖面的相关向量机算法

提出了利用地基双通道水汽微波辐射计探测大气水汽、温度和折射率剖面的相关向量机反演算法,基于青岛地区的历史探空数据和仿真得到的双通道水汽微波辐射计亮温训练了相关向量机网络.青岛地区的实验和仿真比较表明:相关向量机反演得到的剖面与实际大气剖面有较好的一致性.     

制导系统用的毫米波雷达和辐射计传感器

<正> 前言目前正在进行研制用于各种武器(包括空—地和地—地导弹以及自由下落的炸弹)的毫米波雷达和辐射计传感器设备。其目的是:在不利的气象条件下,用电子设备并在无人辅助下而能获得精确坐标,且能提高制导精度。整个研制工作的作用是:使武器更能够自动导向,提高杀伤率,并能从整个武器系统中消除人的因素。甚至在从理论上已     

Modeling the visibility of breast malignancy by a microwave radiometer

A breast tumor is visible by a passive microwave radiometer if it changes the radiometric output of a healthy breast to an extent that overcomes the radiometric resolution for the given sensing antenna and integration time. We modeled breast temperature by the standard Pennes equation using thermal parameters found in the literature for normal and cancerous breast tissue. An apparent thermal volume and its dependence on blood perfusion have been estimated. The radiometric weighting function has been evaluated as a function of the size of a contacting antenna modeled as an aperture antenna. For comparison with the radiometric resolution, the difference signal between the outputs in the presence of a lesion and in its absence has been evaluated for different tumor sizes and depths. The results of the numerical analysis show that this difference signal depends on the average over-temperature in the lesion times the heating efficiency, given by the fraction of power delivered to the tumor when the antenna radiates onto the breast in active modality. A tumor of 6 mm (10 mm) diameter is visible by a 0.1 K radiometer and a 3 cm aperture antenna when it is not deeper than 1.2 cm (2.8 cm) under the assumption of ideal radiometer and antenna.     

Bistatic radar scattering by a chaff cloud

The bistatic radar scattering cross section of a chaff cloud is investigated in the ground-based system for arbitrarily polarized transmitters and receivers. The chaff cloud considered consists of a large number of identical thin conducting wires whose thickness is very small compared to their length and to the wavelength. Numerical results for bistatic cross sections for the cases of orientations uniform in azimuth and Gaussian in elevation, and also for uniformly random orientation in both azimuth and in elevation are presented in the form of three-dimensional graphs, for a few typical examples     

Optimum interpolation of imaging microwave radiometer data

A technique of interpolating imaging microwave radiometer data is presented as an application of the Backus-Gilbert theory. The interpolation process is optimal in the sense that it attempts to preserve the spatial resolution of the antenna gain function associated with the sampled radiometer data. The technique is applied to the Special Sensor Microwave/Imager (SSM/I) satellite data and is found to enhance the high-resolution features of the imagery     

Calibration procedure of a microwave total-power radiometer

A total-power radiometer built in combination with a beacon receiver is being used for low-level attenuation measurements. This experimental receiver was built to measure atmospheric propagation impairments, using the ITALSAT satellite 50 GHz signal. The radiometer is mainly used to provide the reference level for the beacon measurements. Its precision should be better than ±3 K, for low attenuation levels, in order to have 0.1 dB accuracy in the attenuation measurements. A suitable calibration procedure is described