光控高温超导衰减器及光斑偏移对其光响应特性的影响

研制了工作于液氮温度的高温超导系统使用的新型光控高温超导微波可变衰减器.该衰减器的实质是利用钇钡铜氧(YBCO)高温超导薄膜极低的微波表面电阻和卓越的激光响应特性,达到了优良的衰减性能.主要结果包括:可独立使用的光控高温超导微波可变衰减器样品尺寸为12 mm×8 mm×0.5 mm,与高温超导系统集成时无需外壳,体积与重量将大幅减小;高温超导衰减器的插入损耗小于0.2 dB,比常规衰减器低1个数量级;高温超导衰减器的可变衰减精度小于0.01 dB,比常规衰减器至少低1～2个数量级;在本实验条件下,当激光光斑中心偏移微带线中心0.3、0.5和0.7 mm时,其衰减器插损将由0.08 dB变为0.05、0.03和0.01 dB,说明激光光斑偏移量是影响YBCO高温超导衰减器性能的重要因素.     

YBCO高温超导微带线的非平衡光响应及其恢复时长

研究了在波长为0.68μm的连续激光辐照下,钇钡铜氧(YBCO)高温超导(HTS)微带线的非平衡光响应特性,并从超导体机制探索和光响应超导器件研制两个角度对实验现象进行讨论。实验观察到高温超导微带线的非平衡光响应阈值,当功率小于15 mW时,以辐射热效应为主;当功率大于15 mW时,出现非平衡光响应。该阈值的发现,是对Zeldov的“热效应”与“光子效应”同时存在理论的进一步完善,并设想了一种新型的高温超导衰减器;研究了高温超导微带线非平衡光响应的恢复时长,当激光功率为45 mW时,恢复时长约为3.5 s,分析了该时长存在的机制及其对光响应超导器件二次激光激励的影响。     

一种宽带低功耗电压可变衰减器的研究

采用微波薄膜混合集成电路工艺设计并实现了一种砷化镓场效应管电压可变衰减器,在DC～20 GHz带宽内插入损耗小于3 dB,最大衰减量22 dB,输入输出端口驻波比小于2.0,衰减动态范围在10 dB以内时衰减平坦度小于1 dB.该衰减器采用单电压源控制衰减量变化,控制电压在-2～0 V内变化时,控制端口电流的实测值低于5μA,具有显著的低功耗优点.     

GaAs单片集成宽带衰减器

介绍GaAs单片集成衰减器的研究与制作。所研制的衰减器在DC—10GHz的频率范围内，插入损耗小于1．5dB，衰减量大于15dB，驻波小于2．0：1；其中在DC—6GHz的频率范围内，衰减量大于25dB．驻波小于1．5：1，衰减波纹小于0．5dB。     

高功率微波可变衰减器

介绍了高功率微波可变衰减器的设计和测量结果.刀形衰减器的衰减片由通水的聚四氟乙烯制成,利用槽波导技术和截止波导技术,降低了衰减器的漏能。衰减量的变化范围是0-10dB。在工作频段内除少数测量点之外，驻波比小于1.1，可以安全使用。     

全光纤热光型可变光衰减器的闭环控制

根据全光纤热光型变光衰减器(FTOVOA)的光电特性提出了针对该型FTOVOA的闭环控制的设计,并研制了该型FTOVOA的闭环控制系统.实验结果表明,当FTOVOA衰减量小于35dB时,闭环控制系统使光衰减量漂移小于±0.23dB.通过引入闭环控制不仅改善了全光纤热光型可变光衰减器的稳定性,而且使这种电流控制型的可变光衰减器变为一种电压控制型器件.     

MMIC芯片衰减器的设计与检测

本文提供了一种单片微波集成电路(MMIC)芯片衰减器,采用氮化钽薄膜作为电阻材料,利用嵌套掩膜刻蚀技术将芯片衰减器结构一层一层套刻在陶瓷基片上。主要研究了利用氮化钽薄膜电阻制作芯片衰减器的优点,结合HFSS仿真软件,建立3 dB和10 dB芯片衰减器的有限元模型,并对实物产品进行测试验证。试验结果表明:3 dB芯片衰减器在DC～20 GHz工作频率内有较好的衰减响应,回波损耗在整个宽频带内都小于-20 dB,衰减量偏差在DC～12 GHz工作频率内小于±0.3 dB。10 dB芯片衰减器在DC～20 GHz工作频率内也有较好的衰减响应,回波损耗在整个宽频带内都小于-19 dB,衰减量偏差在DC～12 GHz工作频率内小于±0.35 dB。     

M—IDG结构小型超宽带衰减器的FDTD仿真和实现

本文在分析新型传输线-微带加载插入介质波导(M-IDG)基本特性的基础上,用FDTD法仿真设计了小型、超宽带衰减器。电路尺寸分5．1×25mm２和5．1×40mm2两种。对于10dB衰减器,工作频带0．5～18GHz内衰减起伏小于1.0dB;30dB衰减器,在2．0～18GHz带宽内,衰减起伏小于2．5dB。实测结果与FDTD仿真结果基本吻合。     

(10～20)GHz低附加相移数控衰减器设计

基于GaAs 0.25 μm pHEMT工艺，设计一款高精度、低附加相移数控衰减器。该低附加相移数控衰减器由6位衰减单元级联组成，衰减范围为（0～31.5）dB，步进为0.5 dB。在（10～20）GHz工作频率范围内，衰减器插损小于4.8 dB，所有衰减状态衰减精度不大于±0.5 dB、附加相移不大于±3°，输入驻波系数不大于1.4，输出驻波系数不大于1.5。     

一种新颖的DC—50GHz低插入相移MMIC可变衰减器

介绍了一种新颖的DC－50GHz低相移、多功能的GaAs MMIC可变衰减器的设计与制作，获得了优异的电性能。微波探针在片测试结果为：在DC－50GHz频带内，最小衰减≤3.8dB，最大衰减≥35&;#177;5dB，最小衰减时输入／输出驻波≤1.5，最大衰减时输入／输出驻波≤2.2，衰减相移比≤1.2&;#176;/dB。芯片尺寸为2.33mm&;#215;0.68mm&;#215;0.1mm。芯片成品率高达80％以上，工作环境温度达125℃，可靠性高，稳定性好。     

DC-to-20-GHz MMIC multibit digital attenuators with on-chip TTLcontrol

Broadband digital attenuators (DC to 20 GHz) featuring on-chip translators for direct TTL control have been designed and fabricated for MMIC insertion into advanced EW systems. The MMIC digital attenuators utilize a novel distributed topology to provide exceptional performance parameters include through-state insertion losses of less than 5 dB for a 4-b attenuator, 4 dB for a 2-b attenuator, 2 dB for a switched attenuator, and normalized mean attenuation accuracies within 0.5 dB from DC to 20 GHz for each attenuator. When cascaded, this set of digital attenuators provides the high-dynamic range (>75 dB) required for advanced EW system applications     

A Precision Compact Rotary Vane Attenuator

The accurate attenuation range of many precision rotary vane attenuators is limited to about 40 dB because of a transmission error term that is not accounted for in the familiar cos/sup 2//spl theta/ attenuation law. This paper presents a modified law that makes it possible to extend the useful dynamic attenuation range. The same modified law also makes it practical to reduce the length of the rotor section and, therefore, to develop compact rotary vane attenuators that are accurate over reduced dynamic attenuation ranges. The modified law requires the additional calibrations of the incremental attenuation and incremental phase change at the 90/spl deg/ vane angle setting. To verify the modified law, a precision compact WR 112 rotary vane attenuator was fabricated and tested. The attenuator has a total dynamic attenuation range of about 30 dB and a rotor section length approximately one-third that of a conventional WR 112 attenuator. Application of the modified law resulted in good agreement between theoretical and measured incremental attenuations over the total dynamic attenuation range.     

Superconducting quasi-lumped element filter on R-plane sapphire

Recent advancement in superconducting microwave technology has led to commercial deployment of high-temperature superconducting (HTS) subsystems for wireless communication applications. Commercialization of the HTS thin-film devices lies within, among other factors, the quality and consistency of the HTS film, as well as the overall cost and performance of the subsystem. In this paper, we present the design and performance of a quasi-lumped element filter on sapphire substrate. Centered at 1857 MHz with 0.8% fractional bandwidth, the six-pole Chebyshev filter has an insertion loss of less than 0.2 dB at 60 K, which translated into a realized unload Q of 35000. This is an important step toward the commercialization of superconducting devices using industrial standard wafers. With the continuous improvement of the HTS film quality, YBCO film on sapphire could be an answer to the future     

一种简单的高温超导连续通带双工器设计

在双抛LaAlO3衬底上外延生长的钇系高温超导薄膜YBCO的基片上,设计并制作一个四级高温超导连续通带双工器（工作频率3.0～3.5GHz和3.5～4.0GHz）,与常规金属材料的双工器相比,体积减少3/4,插损减少2dB。在液氮温区77K时,测试结果为：通带内插损小于0.8dB,通带间带外抑制大于30dB通带中心频率。为近一步研制高温超导多工器提供了很好的借鉴,对将来高温超导信道化接收机系统的研究和设计具有重要的意义。     

A novel, linear voltage variable MMIC attenuator

Voltage variable attenuators (VVAs) for microwave applications that are fabricated using present technology and design methods feature a nonlinear relationship between the attenuation measured in decibels and the control signal. A novel VVA that features a linear attenuation-control-voltage relationship without the need for external linearization is described. This is accomplished by connecting a number of FET segments in a unique fashion to form a composite FET. The channel resistance of the composite FET constitutes a prescribed function of its gate-source voltage. By careful design the resistance functions that are necessary for realization of linear attenuators are synthesized. The attenuator was fabricated using GaAs MMIC technology employing MESFETs as voltage variable resistors. It is completely passive and does not require a DC supply. The attenuation ranges from 2 to 15 dB over DC to 8 GHz while port impedance is kept close to 50 Ω. The deviation of the attenuation from a straight line is less than 0.2 dB     

Radiation-induced attenuation in Co2+-doped fibreattenuators

Long-term resistance of Co²⁺-doped fibre attenuators exposed to gamma-ray irradiation was investigated. The attenuation increase during 25 years is predicted to be 0.004 dB for a 20 dB attenuator, which consists of a 1.5 dB/m attenuation fibre, in the worst case encountered in undersea conditions     

Voltage-controlled PIN diode attenuator with a temperature-compensation circuit

This paper presents a voltage-controlled PIN diode attenuator and its temperature-compensation circuit composed of a thermistor and simple operational amplifier circuits. After carefully investigating the temperature characteristics of PIN diode attenuators, we designed voltage-controlled PIN diode attenuators showing the linear attenuation characteristics of 16 dB with input voltage within the operating temperature range. The fabricated attenuator has demonstrated the improvement of attenuation variation from 15 to 0.5 dB in the temperature range from -15 to 65/spl deg/C.     

Ku波段6bit数字衰减器MMIC的小型化设计

基于0.25μm GaAs增强/耗尽(E/D)型赝配高电子迁移率晶体管(PHEMT)工艺,设计并实现了一款集成了6 bit并行驱动器的数字衰减器单片微波集成电路(MMIC)。该衰减器采用T型衰减网络结构,不仅缩小了芯片面积,并且可实现较好的衰减精度和衰减附加相移。芯片在片测试结果表明,在-5 V电源电压下驱动器的静态电流为1.8 mA,响应速度为25 ns。在9~18 GHz频率范围内,衰减器芯片的插入损耗不大于3.6 dB,均方根衰减精度不大于0.7 dB,衰减附加相移为-2°~4°,输入电压驻波比(VSWR)不大于1.25∶1,输出VSWR不大于1.5∶1。芯片尺寸为1.6 mm×0.6 mm×0.1 mm。该电路具有响应速度快、功耗低、面积小、衰减附加相移小等优点,可广泛应用于通信设备和微波测量系统中。