LiTaO3相位调制器扩频特性的研究

介绍一种利用开关微波信号调制LiTaO3电光晶体．实现对输入光扩频的方法。研究了LiTaO3相位调制器的理论模型．并给出了相应的计算公式。利用公式模拟、计算得到在一定做波功率调制下相位调制器输出的扩频光谱。给出了实际系统的框图，并对实际系统的输出光谱进行测量．得到在不同微波调制功率下的光谱图。对理论计算所得的输出光谱与实际系统的输出光谱进行分析．发现谱线情况较一致．仅对应的微波输入功率有差异．原因是实际系统中微波传输线阻抗不匹配．所需的实际微波功率比理论值大。该系统的电光晶体为LiTaO3．激光器工作波长为1053nm，微波频率为4．3GHz．开关信号是重复频率为1kHz．占空比为4：6的方波。使90％的光功率分散于主峰以及一、二次边频，且一、二次边频的功率近似相等。     

宽带微波限幅器模块的研究

采用微波混合集成电路设计方法，用二只并联 ＰＩＮ二极管芯片和一只检波二极管芯片，在很小的腔体内制作了微波限幅器模块。其电参数为：频率范围 ｆ＝１．０～５．０ＧＨｚ，插入损耗ＩＬ≤０．４３ｄＢ，输入输出电压驻波比ＶＳｗＲ≤１．５，漏功率Ｐｌｉｍ≤１．８ｍＷ（输入功率为连续波１Ｗ时）。     

高效94GHz0.15μm InGaAs／InAlAs／InP单片功率HEMT放大器

介绍了采用栅长为０．１５μｍ的钝化Ｉｎ０．５３Ｇａ０．４７Ａｓ／Ｉｎ０．５２Ａｌ０．４８Ａｓ／ＩｎＰＨＥＭＴ的高效Ｗ波段功率单片微波集成电路（ＭＭＩＣ）。０．１５×３２０μｍ单级ＩｎＰ功率ＨＥＭＴＭＭＩＣ放大器在９４ＧＨｚ时的最大功率附加效率为２３％，输出功率为４０ｍＷ，功率增益为４．９ｄＢ。当电源偏置成更高的输出功率时，在９４ＧＨｚ处可得到功率附加效率为２０％的５４ｍＷ的输出功率。这些结果表明，在此频率下，这样的效率和输出功率是迄今为止所有报道中最佳的。     

P波段脉冲调制激励放大组件

叙述一种Ｐ波段脉冲调制激励放大组件的设计方法及测试结果，采用微波单片集成电路和微波功率晶体管内匹配技术，制作出５４０～６１０ＭＨｚ下增益Ｇｐ≥３０ｄＢ、输出功率Ｐｏ≥５Ｗ±０．５ｄＢ的脉冲功率放大器。     

P波段脉冲调制激励放大组件

叙述一种Ｐ波段脉冲调制激励放大组件的设计方法及测试结果，采用微波单片集成电路和微波功率晶体管内匹配技术，制作出５４０－６１０ＭＨｚ下增益ＧＰ≥３０ｄＢ、输出功率ＰＯ≥５Ｗ±０．５ｄＢ的脉冲功率放大器。     

低泄漏限幅器的研究

采用混合集成电路设计方法，用ＰＩＮ二极管和检波二极管，在很小的腔体内制作了小型化夫源微波限幅器。电参数为：频率ｆ＝２．５～３．０ＧＨｚ，插入损耗ＩＬ≤０．３９ｄＢ，电压驻波比ＶＳＷＲ≤１．３，漏功率Ｐｌｉｍ≤０．５５ｍＷ（输入连续波１Ｗ）。     

微波脉冲功率合成放大器的研制与应用

本文以双极晶体管ＲＺ２８３３Ｂ４５Ｗ为例，简单介绍了按阻抗匹配法设计的微波脉冲功率放大器，输出功率５２Ｗ，增益为７．１６ｄＢ。将两路同样的放大器进行功率合成，输出功率可达９５Ｗ，合成效率为９０％以上。利用多路功率合成可得到更大的输出功率。本文还简单介绍了利用功率合成技术制作的Ｓ波段脉冲遥测发射机，此机采用ＦＭ－ＡＳＫ调制方式，有缓变、特快和波形三个传输通道，是一种有应用前途的脉冲遥测发射机。     

高增益硅超高频功率SIT

采用全自对准介质盖栅工艺，通过合理设计，研制成功一种高增益硅超高频功率ＳＩＴ。在４００ＭＨｚ工作频率，５０Ｖ工作电压下，其输出功率Ｐ０为４０Ｗ，漏极效率η０接近６０％，功率增益Ｇｐ，高达１６ｄＢ，Ｐ０＝２５Ｗ时，三阶交调３ＩＭ为－１６ｄＢ，Ｐ０＝２．５Ｗ时，３ＩＭ为－５０ｄＢ。     

大光学深度波长调制吸收光谱的研究

由于在高光学深度下,比尔-朗伯特(Beer-Lambert)定律的线性近似不再成立,波长调制光谱(WMS)中常用的偶次谐波探测失效.比较研究了适用于高光学深度的对数光谱方法和比值方法,理论研究了这两种方法的测量分辨率以及信号幅度随光学深度变化的规律,研制了一套波长调制光谱光纤甲烷传感器.得到了对数方法中光源功率调制的傅里叶系数表达式;研究了制约对数光谱方法和比值方法分辨率的因素.研究表明,对数光谱方法的测量分辨率高于比值方法2～3个数量级.     

用于甲烷气体传感的1．67μm掺Tm~（3＋）光纤荧光光源的实验研究

从甲烷气体相关光谱检测法对光源的要求出发，试制了几种不同参数的Ｔｍ（３＋）掺杂光纤，在实验上用７８８ｎｍ半导体激光器泵浦，测量了泵浦端出射的荧光光谱及总功率．在１．６７μｍ处荧光功率密度达到０．２５μＷ／ｎｍ，比用白炽灯作光源耦合多模光纤所得的结果高出８倍多，是一种较为理想的适用于甲烷气体检测的宽带光源。     

Temperature Dependence of High Frequency and Noise Performance of Sb-Heterostructure Millimeter-Wave Detectors

The temperature dependence of the microwave and noise performance of zero-bias Sb-heterostructure backward diodes for millimeter-wave detection have been investigated experimentally. Both the junction capacitance and junction resistance were found to decrease with decreasing temperature, while the intrinsic cutoff frequency and sensitivity are observed to increase as the temperature is lowered. A simple physical model that captures these effects is described. The directly measured voltage sensitivity at 50 GHz for a 2times2 mum ² device increased from 3650 V/W at room temperature to 7190 V/W at 4.2 K. The measured noise equivalent power (NEP) decreased from 4.2 to 0.2 pW/Hz^1/2 as the temperature was lowered from 298 K to 4.2 K when driven from a 50- Omega source. Based on the measured RF sensitivity, S-parameters, and noise spectrum, a NEP of 0.3 pW/Hz^1/2 is projected for room-temperature operation at zero bias using a conjugately matched RF source     

44 GHz waveguide-based power amplifier module using doubleantipodal finline transitions

A 44 GHz waveguide-based power amplifier module was developed using the double antipodal-finline transitions which also serve as a power combiner. The measured insertion loss of the proposed combiner was ~0.9 dB per transition around 44 GHz. The fabricated power amplifier module combining two 0.93 W monolithic microwave integrated circuit power amplifiers showed a saturated output power of 1.4 W with a high combining efficiency of 75% at 44 GHz     

Experimental study on an S-band near-field microwave magnetron power transmission system on hundred-watt level

A multi-magnetron microwave source, a metamaterial transmitting antenna, and a large power rectenna array are presented to build a near-field 2.45 GHz microwave power transmission system. The square 1 m² rectenna array consists of sixteen rectennas with 2048 Schottky diodes for large power microwave rectifying. It receives microwave power and converts them into DC power. The design, structure, and measured performance of a unit rectenna as well as the entail rectenna array are presented in detail. The multi-magnetron microwave power source switches between half and full output power levels, i.e. the half-wave and full-wave modes. The transmission antenna is formed by a double-layer metallic hole array, which is applied to combine the output power of each magnetron. The rectenna array DC output power reaches 67.3 W on a 1.2 Ω DC load at a distance of 5.5 m from the transmission antenna. DC output power is affected by the distance, DC load, and the mode of microwave power source. It shows that conventional low power Schottky diodes can be applied to a microwave power transmission system with simple magnetrons to realise large power microwave rectifying.     

一种紧凑型大功率微波固态源

传统的微波源主要由行波管、磁控管、返波管等电真空器件实现,但因其工作电压高、功耗大、体积大,导致在使用安全性、利用效率和便携性等方面存在不足。而微波固态源由于具有效率高、谐波抑制性能好、稳定性高等优点,正逐步替代传统微波源,有着很好的发展空间。设计了一种紧凑型大功率微波固态源,采用锁相环作为信源,通过三级功放级联对微波信号进行逐级放大,最终输出频率为915 MHz、功率为300 W 的微波信号。测试结果表明该固态源的工作效率≥70%,二次谐波抑制≤-40 dBc,三次谐波抑制≤-50 dBc。该设计在微波加热和解冻等方面具有很好的应用前景。     

Low phase-noise microwave oscillators with interferometric signal processing

Phase-noise spectral density of a 9-GHz oscillator has been reduced to -160 dBc/Hz at 1-kHz offset frequency, which is the lowest phase noise ever measured at microwave frequencies. This performance was achieved by frequency locking a conventional loop oscillator to a high-Q sapphire dielectric resonator operating at the elevated level of dissipated power (/spl sim/0.4 W). Principles of interferometric microwave signal processing were applied to generate the error signal for the frequency control loop. No cryogenics were used. Two almost identical oscillators were constructed to perform classical two-oscillator phase-noise measurements where one oscillator was phase locked to another. The phase locking was implemented by electronically controlling the level of microwave power dissipated in the sapphire dielectric resonator.     

Internal stress in MPCVD diamond films on the Si substrate based on XRD line shape

The diamond films adherent to Si substrate are deposited with the microwave plasma CVD （MPCVD） at microwave powers of 6000 W and 4000 W fTom 6 h to 10 h, respectively, the internal stresses of the films are measured by XRD. Spectral peak shift and widening arc applied to calculate the magnitudes of macro and micro stresses. The results show that the macro stress is tensile. The internal stress can be controlled by the microwave power. With the microwave power increasing,the intrinsic and macro stresses decrease, and the micro stress increases significantly. Also, it can be found that the macro and micro stresses increase with deposited time when the other conditions are the same.     

Dehydrating of flax fiber with microwave heating for biocomposite production.

The feasibility of microwave dehydrating flax fiber was evaluated using a commercial domestic microwave oven at four power settings representing 200, 300, 400 and 500 Watt (W) power level. Due to the possibility of local heating and consequent fiber degradation, the changes in color of the flax fiber at different levels of temperature were also investigated. The dehydration processes at various power levels were simulated by Page model. Based on visual inspection, color analysis and scanning electron microscopy (SEM) of the fiber, it was revealed that discoloration of the fiber occurred at about 170 degrees C. At 200 and 300 W power level, after 10 minutes of dehydrating, the moisture content of the fiber reached from initial 7.9% close to 2.0 and 1.0%, respectively. For 400 W power level, the moisture content of the fiber dropped to 0. 10% in about 9.5 minutes. Major discoloration of the fiber was noticed when dehydration was proceed beyond 4.5 minutes for 500 W treatment. The Page model very well fitted the experimental data. The coefficients of determination calculated from the model and the experimental data increased with increase in applied microwave power     

小功率微波微等离子体源的集成研究

提出了一种小功率集成微波微等离子体源的结构,通过平面微带渐变螺旋电感耦合线圈激励微波微等离子体。研究表明,该集成微波微等离子体源具有频率可调、功率可调的特点,频率范围为2. 3 ~ 2. 6GHz,输出功率范围为20 ~40dBm。在频率为2477MHz、空气真空度为3. 7 Torr,输入功率为2. 15W 时,平面微带渐变螺旋电感耦合线圈能较好激励起微波微等离子体,这为微波微等离子体源的小型化研究提供了基础。     

高散热性能TGV转接板

随着玻璃通孔(TGV)转接板在微波系统集成中的应用越来越广泛,其微波大功率应用情况下的散热性能成为研究重点。针对TGV转接板高效散热性能的要求,进行TGV散热结构的设计和性能分析。建立TGV转接板封装集成结构的有限元模型,设计TGV转接板铜柱阵列散热结构。通过TGV工艺制作TGV高密度阵列。在4.82~14.47 W功率范围内对TGV转接板的散热性能进行测试,相应的TGV散热结构区域的热流密度为40.03~120.18 W/cm²,测得热阻芯片表面温度高达54.0~126.5℃,低于微波功率芯片最高结温150℃,可以满足大功率微波系统集成高效散热的需求。