Microwave reflection and transmission measurements for pulmonary diagnosis and monitoring

The potential of using low intensity penetrating microwave energy in diagnosis and monitoring of pulmonary diseases such as edema and emphysema has been investigated theoretically and in selected animal models. These diseases are characterized by changes in total lung water which modify the permittivity and conductivity of the lung tissue, and consequently affect the microwave reflection from or transmission through the lung. Both reflection and transmission measurement techniques have been examined. Animal experiments have indicated changes in microwave reflection with lung water changes. The diagnostic capabilities of transmission measurements have been evaluated experimentally on a phantom model, and theoretically on a planelayered tissue model.     

Microwave photoconductivity and photodielectric effect in thin PbS films obtained from thiocarbamide coordination compounds

The dependences of photoresponse parameters of the microwave absorption caused by the effect of a short pulse of a nitrogen laser (337 nm, 10 ns) in micrometer-thick PbS films on the frequency of a microwave oscillator, intensity of light, and conditions of the film growth are investigated by a cavity method in the 3-cm frequency band. The films were obtained by pyrolysis of aerosol of thiocarbamide coordination compounds at a substrate temperature of 250–500°C. Using the analysis of frequency dependences of the photoresponse, the microwave photoconductivity and the photodielectric effect, which cause a variation in the cavity quality factor and a variation in its resonance frequency, respectively, are investigated separately.     

微波等离子灯微波系统的改进

传输微波的波导和形成谐振腔的网罩足微波等离子灯中的核心部件,本文重点阐述这两部分微波系统的仿真优化设计.文章首先分析了最早所采用的微波传输系统,给出仿真结果论证,然后介绍和参考了国外优秀的波导及谐振腔设计方案,给出理论分析,最终依据以上综合分析提出新型波导系统以及新型谐振腔的设计,其中部分新型设计已在实际应用中取得了很好的效果,其它新型设计还将继续研究,如文中提到的脊型谐振腔和半椭球谐振腔.     

我国微波技术与微波通信的进展

本文论述我国在微波通信领域已取得或正在开展的一些基础性研究工作以及发展状况。包括微波技术方面的发展水平；微波通信的几种主要形式及其发展水平。     

微波功率模块微波特性的研究

集成固态/真空电子技术的微波功率模块(MPM)是新一代电子武器装备的"超级微波元器件".文中对MPM微波特性进行了研究,由于行波管(TWT)良好的色散特性,使MPM具有宽频带和功率、带宽乘积的优点;又由于固态放大器(SSA)低噪声性能,使MPM具有低噪声特性;高稳定的集成电源(IPC)决定了MPM具有低相位噪声与低杂散的频谱特性,合理的增益分配也使得MPM具有良好噪声特性.文中具体分析了集成电源(IPC)性能对频谱特性的影响,SSA与TWT噪声特性、增益分配对MPM噪声特性的影响,MPM幅相一致性和功率合成效率问题,并给出了仿真曲线,通过对某X波段MPM微波特性测试,验证了MPM优越的性能,也充分表明了MPM具有广泛的应用前景.     

LTCC微波多芯片组件中键合互连的微波特性

键合互连是实现微波多芯片组件电气互连的关键技术,键合互连的拱高、跨距和金丝根数对其微波特性具有很大的影响。本文采用商用三维电磁场软件HFSS和微波电路设计软件ADS对低温共烧陶瓷微波多芯片组件中键合互连的微波特性进行建模分析和仿真优化。仿真优化结果与LTCC试验样品的测试结果吻合较好。     

Microwave cataractogenesis

Experimental investigations of microwave cataractogenesis, as well as the application of theoretical methods, suggest the involvement of thermal damage. Time-intensity cataract thresholds for acute exposures of rabbits indicate dose reciprocity. The induction of lens opacification following repeated exposure at intensities below the threshold for single-dose exposures suggests a cumulative component of lens damage and the existence of repair mechanisms. Repair mechanisms are also indicated, in experimental biochemical studies of microwave effects on rabbit lens epithelial cells with a 10-20-day cellular recovery period. Experimental studies have revealed a relationship between the site of ocular damage and radiation wavelength. Cataract induction has also been reported in humans accidentally overexposed to microwave radiation. Although dosimetric data is not adequate to specify exposure thresholds, acute lens opacification in humans appears to involve thermally induced lens damage that occurs at exposure intensities of 100 mW/cm²or greater. Epidemiological studies of workers have in some instances suggested that occupational microwave exposure may result in lens alterations but there is no evidence that such effects are associated with visual impairment or cataract formation.     

Microwave acoustics

During the last few years, generation and propagation of acoustic waves have been extended to frequencies high into the gigacycle region. This paper deals with microwave acoustics, with emphasis on effects and techniques utilized at cryogenic temperatures. The extremely short wavelengths require the use of single crystal propagation media, free from defect scattering, supercooled to reduce wave attenuation from phonon interactions. Interactions of acoustic phonons with other phonons, electrons or holes, and spin waves are possible, with interchanges of energy that can produce attenuation or amplification of acoustic waves. The fundamental characteristics of acoustic wave propagation in crystanine media are discussed, with a review of experimental techniques and results. Microwave acoustic waves in solids and transducers suited to generation and detection are discussed, and a basic analysis of plane wave piezoelectric coupling is presented.     

Microwave Photonics

The low-loss wide bandwidth capability of opto-electronic systems makes them attractive for the transmission and processing of microwave signals, while the development of high-capacity optical communication systems has required the use of microwave techniques in optical transmitters and receivers. These two strands have led to the development of the research area of microwave photonics. This paper reviews the development status of microwave photonic devices, describes their systems applications, and suggests some likely areas for future development     

Microwave electronics

Ohne Zusammenfassung     

Microwave Apexcardiography

A microwave technique for recording apexcardiograms is reported. The technique is based on detecting changes in the reflected microwaves caused by movement of the chest wall in response to left-ventricle activity. Results show that microwave technique is useful for delineating the fine structures in the precordial movement.     

微波辐射计

本文介绍了3厘米微波辐射计的部件性能、特点及测试结果.工作在9.375GHz下的反馈式零平衡辐射计,在0.2秒积分时间下,温度分辨率叶达0.6°K以下,其测量范围为100～300°K,辐射计带宽为120MHz.     

Microwave Photonics

Broadband and low loss capability of photonics has led to an ever-increasing interest in its use for the generation, processing, control and distribution of microwave and millimeter-wave signals for applications such as broadband wireless access networks, sensor networks, radar, satellite communitarians, instrumentation and warfare systems. In this tutorial, techniques developed in the last few years in microwave photonics are reviewed with an emphasis on the systems architectures for photonic generation and processing of microwave signals, photonic true-time delay beamforming, radio-over-fiber systems, and photonic analog-to-digital conversion. Challenges in system implementation for practical applications and new areas of research in microwave photonics are also discussed.      

Microwave superconductivity

This paper provides an overview of the microwave applications of high-temperature superconductor (HTS) technology. The main characteristics of HTS materials are outlined, highlighting the differences between superconductors and normal conductors. This paper presents recent progress in the development of HTS filters, multiplexers, cryogenic receivers, delay lines, and antennas. A brief summary of cryocooler technology and cryopackaging requirements is presented. The benefits of using HTS technology in wireless and satellite systems are also discussed. The intent of this paper is to provide perspective to newcomers in the field and to empower the potential end-users with current status and performance capabilities of HTS microwave devices     

微波检测模块

从微波电路、运放及数字电路、脉冲检测等方面介绍了微波检测模块，给出了有关数据并对问题进行了讨论。     

Microwave holography

Using Gabor's two-step imaging process, a hologram has been constructed with microwave radiation at 16 GHz, and image reconstruction has been accomplished at optical wavelengths using a 6328 Å laser source. For this hologram a phased receiving array sampled the scattered field in the vertical direction, while the object rotation resulted in the generation of a synthetic array in the horizontal direction.     

Microwave Generation Based on Optical Domain Microwave Frequency Octupling

A novel approach to achieving microwave frequency octupling in the optical domain is proposed and demonstrated. The proposed system consists of two cascaded Mach-Zehnder modulators (MZMs) that are both biased at the maximum transmission point, with a tunable optical phase shifter connected in between to introduce a phase shift. An input microwave signal is applied to the MZMs with its power adjusted to ensure the two MZMs having an identical phase modulation index. A theoretical analysis that leads to the conditions for achieving frequency octupling is provided. The approach is verified by experiments. The phase noise performance and the frequency tunability are also experimentally investigated.     

微波等离子体激发用大功率微波模式转换器

设计了大功率微波模式转换器,并采用两种工艺加工,分别利用低功率冷测和大功率热测实验对比了其性能。结果表明,导电氧化的加工件性能要明显优于老化件,其低功率冷测传输效率可达99.9%,返回损耗降低至-29.12 dB,大功率热测实验表明,采用导电氧化工艺的模式转换器镀膜质量要整体优于老化件的镀膜质量。