宽带X波段波导结环行器的研究

为了满足某系统的要求,需研制带宽在X波段达4GHz（40％）的宽带波导结环行器。文中采用Y形脊波导中心结形式,采用三阶等宽切比雪夫阶梯阻抗匹配器实现环行器宽带阻抗匹配,并利用HFSS软件优化环行器结构。设计的环行器实验结果为：在8．4GHz至12．4GHz范围内,插损不大于0．3dB,隔离不小于20dB,驻波不大于1．2。环行器设计结果与实验结果基本一致,表明该设计方法正确,设计的环行器满足系统宽带要求。     

Ku波段自偏置微带双Y结环行器的设计和制作

目前商用环行器均需要外加偏置磁场,体积大,难集成。利用厚度为0.2mm的锶永磁铁氧体材料,基于带线结环行器理论,设计、优化并制作了一种自偏置微带双Y结环行器,器件无需外加偏置磁场,可显著降低环行器的体积和重量,便于集成化。测试结果和仿真结果基本吻合。测试结果表明,制作的器件在17.5GHz和29.3GHz频率点处均呈现明显的环行性能。在17.5GHz处,电压驻波比为1.3,插入损耗为4.2dB,隔离损耗为20.4dB。在29.3GHz附近,隔离损耗为18.1dB。在30.3GHz附近,插入损耗为3.1dB,电压驻波比约为1.2,最后探讨了所制作的环行器的插入损耗偏大的原因。     

厚膜导带材料微波性能的研究

本文讨论了国产厚膜导体材料的微波性能。用国产Au浆料和Pd—Ag浆料,通过传统的厚膜工艺,在99％Al_2O_3陶瓷基片上制作了一组特性阻抗为50欧姆的微带线。用薄膜技术制作了几条和厚膜微带线一样的薄膜微带线。使用HP8410S网络分析仪测出了频率在2～12GHz范围内各条微带线的散射参数的幅度和相位。对微带线的损耗测量值和理论值进行了比较。用台阶测试仪测绘出了微带线中心导体的截面膜厚分布图。实验结果表明:在频率8GHz下,国产Au厚膜微带线的损耗和薄膜微带线的损耗几乎相等。另外,用国产Au浆料制作了一个3dB分支线定向耦合器,器件的性能良好。     

厚膜微波混合集成电路研究

研究比较了不同金属导电浆料、基片等厚膜材料的微波特性,发现通过改进厚膜工艺可使这种材料的应用领域大大扩展,并可推至微波频率下工作。引入厚膜腐蚀新工艺制得边缘齐整的、分辨率达25μm的厚膜精细线条及间隙。应用计算机辅助设计(CAD)技术及厚膜新工艺,设计制作了一种微波宽带放太器,其频带为3～7GHz,增益10±1dB,噪声小于5.7dB。另外还设计制作了性能优良的厚膜微波带通滤波器(中心频率7.7GHz)和3-dBLange耦合器,(中心频率为6GHz)。这些电路、元件用传统厚膜工艺是无法实现的。     

（英）钡铁氧体薄膜自偏置毫米波环行器设计与制备

基于厚度为10 μm的钡铁氧体薄膜设计,制备了共面波导结构的毫米波薄膜环行器.这种薄膜环行器不需要外加磁体,在34 GHz和37.6 GHz显示出环行特性,其非互易效应大于15 dB.结果表明,采用共面波导结构可以实现薄膜环行器.这种薄膜环行器具有和单片微波集成电路集成的潜在应用.     

自偏置钡铁氧体微带结环行器的研究

本文采用HFSS微波仿真软件设计了中心频率在25GHz的微带结环行器,仿真结果表明,该环行器在中心频率附近的插损S12为2dB,隔离S21为20dB。根据设计的结构参数,采用半导体工艺制作了微带结环行器,测试结果表明,该环行器在中心频率25.6GHz附近的插损S12为14.9dB,隔离S21为22.4dB,显示了初步的环行性能。     

电控X波段快速开关环行器的研制

电控快速开关环行器属非均匀磁化场激励器件，如采用设计常规环行器的均匀磁化场方法误差很大，该文介绍了基于软件Maxwell3D和HFSS的混合有限元方法来设计X波段电控快速开关环行器的过程。研制的器件性能经测试为；以10GHz为中心约1．3GHz频带内，插损不大于0．3dB，隔离不小于22dB，驻波不大于1．2，开关时间约为3μs。     

基于高取向度多晶SrNi2Sc0.75Fe15.25O27的Ku波段自偏置环行器设计

计及自偏置环行器插入损耗过大,分别从铁氧体材料与器件设计两方面进行研究,以改善自偏置环行器性能。对取向W型六角铁氧体SrNi₂Sc_0.75Fe_15.25O₂₇(SrW)的磁性能进行了阐述,并基于SrW性能参数设计了Ku波段自偏置微带环行器。同时,论述了三角谐振器的环行原理、阻抗匹配原理,并进行了器件仿真分析。由仿真结果可知,自偏置微带环行器在12.4 GHz附近插入损耗为最小值0.51 dB,相应的隔离度为18.58 dB,15 dB带宽为0.94 GHz,电压驻波比小于1.22,表明该环行器在12～18 GHz实现了良好的环行性能。     

毫米波宽带高功率结环行器的研制

为了满足某宽带发射机系统的需求,需研制全Ka波段（26.5～40 GHz）的宽带波导结环行器。本文采用Y形脊波导中心结形式,多级切比雪夫阶梯阻抗匹配器实现环行器宽带阻抗匹配,利用HFSS优化环行器结构。设计的环行器实验结果为：在26.5～40 GHz范围内,插损不大于0.45 dB,隔离不小于19.5 dB,驻波不大于1.4,通过60 W平均功率实验。     

流延法制备铁基吸波电磁厚膜的工艺和吸波性能研究

采用流延法制备了铁基吸波电磁厚膜,通过优化混料工艺制备出的厚膜可以达到200μm厚。通过DSC测试确定了叠层固化温度在130℃,固化后的样品可以用于多层吸波结构。通过实验确定了树脂含量21%(质量分数)的浆料和50～80 g/inch的离型力PET膜润湿性良好,流延膜可以连续收卷。测试了2.6～3.95 GHz内吸波厚膜的电磁参数,用弓形法测试了反射率。研究发现:球状铁粉含量85%(质量分数)的吸波厚膜吸收峰值可达-24 dB,-10 dB以下的吸收带宽为4.2 GHz。制备的球状铁粉和片状铁粉基吸波电磁厚膜样品在2～18 GHz范围内搭配使用可以有效吸收电磁波。     

CPW Circulators with Barium Ferrite Thin Films

A miniaturized circulator using barium ferrite films with a coplanar waveguide(CPW) structure is designed and optimized by high frequency electromagnetic field simulations based on finite element methods.The best circulation performance of the film circulator based on 10 μm thick barium ferrite thin films is obtained with an insertion loss of 0.13 dB and an isolation of 22.89 dB around 36.9 GHz.The microwave characteristics of film circulators with CPW and CPW with ground(CPWG) structures have been compared.The influences of the gap between the ground and the signal line,and the ferromagnetic resonance line width on the microwave properties are also studied.     

Integrated metal magnetic film coupled line circulators for monolithic microwaveintegrated circuits

A new structure of integrated planar metal magnetic film coupled line (MMFCL) circulators is presented, in which a metal magnetic film is used instead of ferrite materials. Simulation was performed with HFSS based on coupled-mode theory. An insertion loss of 4 dB and isolation of -13.5 dB between S₂₁ and S₁₂ over a frequency band of 3 GHz (from 36.5 to 39.5 GHz) were realised for a three-port MMFCL circulator     

Wideband Circulators for Use at Frequencies Above 100 GHz to Beyond 350 GHz

High-performance circulators operating at frequencies in the range from 100 to 350 GHz have been developed for application in major measurement systems. These circulators have open quasi-optical structures. The magnetized plates in these devices are of nonmetallic magnetic materials which have both well-developed millimeter-wave gyrotropic properties and the magnetostatic properties of an excellent permanent magnet material. Very few commercially available magnetic materials have been found that meet both the magnetostatic and the magnetooptical selection criteria. Those few have, however, made possible the design, manufacture, and successful operation of high-performance circulators/isolators at these high operating frequencies. Several circulators/isolators of this type have been installed in major measurement systems.     

Leaf overlay effects on the transmittance of thick and thin film microstripline

This paper reports the differences in the transmittance characteristics in the X and Ku band (8–18?GHz) of thick film and thin film microstripline due to leaf overlay. Two types of leaves are studied?—?Tradescantia (Magenta coloured leaf) and Pothas Scandens (Green leaf). The changes in the moisture content in the leaf produces frequency, surface, orientation and type of metallization dependent changes in the characteristics of the microstriplines. Thick film and thin film microstriplines react differently when there is deficiency of chlorophyll in the leaf overlay. An approximate estimate of the effective dielectric constant of the leaf has been made using the overlay technique. It is felt that thick film microstripline with leaf overlay can be used to monitor the moisture status of leafy vegetation in the 8–18?GHz frequency range.     

Circulators using coplanar waveguide

Bosma's method of analysing stripline circulator operation is modified to suit circulators using coplanar waveguide. One of the circulators designed in this way shows a maximum isolation of 19.1 dB, insertion loss 0.8 dB and VSWR 1.3 or less at a centre frequency of 9.56 GHz.     

A High Power 320-356GHz Frequency Multipliers with Schottky Diodes

A 320-356GHz fixed-tuned frequency doubler is realized with discrete Schottky diodes mounted on 50μm thick quartz substrate.Influence of circuit channel width and thermal dissipation of the diode junctions are discussed for high multiplying effficiency.The doubler circuit is flip-chip mounted on gold electroplated oxygenfree copper film for grounding of RF and DC signals,and better thermal transportation.The whole multiplying circuit is optimized and established in Computer simulation technology (CST) suite.The highest measured multiplying efficiency is 8.0％ and its output power is 5.4mW at 328GHz.The measured typical output power is 4.0mW in 320-356GHz.     

A 4-GHz Lumped-Element Circulator (Short Papers)

The successful application of thin-film lumped-element circulators (LEC) at L band has led to the following question: How far can these devices be extended in frequency using our present beam-crossover technology? An exploratory study aimed at building an LEC at approximately 4 GHz was successfully completed. Preliminary tests showed a 20-dB band from 4.2 to 5 GHz with an insertion loss <1 dB (minimum, 0.5 dB). This includes fixture losses, which account for about 0.2 dB. The device has been tuned to operate above 5 GHz, and from the experiments it is concluded that a device of this type could be built at frequencies as high as X band. These devices are very small; at 4 GHz, the circulator junction is a 0.075- in diam.     

适用于厚膜剥离的图形反转双层胶光刻技术

介绍了一种适用于厚膜剥离的图形反转双层胶光刻技术,采用图形反转胶和正型光刻胶,选择合适的光刻工艺形成了光刻胶倒梯形的剖面结构,可以成功剥离与胶层厚度相同的膜层,厚度可达13μm。同时对一些技术机理和关键工艺条件进行了讨论。     

Dissipative Parameters in Ferrites and Insertion Losses in Stripline Y Circulators Below Resonance (Letters)

Extensive microwave loss measurements have been performed at the frequency of 1.3 GHz on below resonance stripline Y circulators loaded with aluminum doped YIG. Extemal x' have been measured on the same compositions. Also, dielectric loss measurements have been carried out. A relation is found which correlates insertion loss in stripline circulators with loss parameters x' and tan /spl delta/.     

Miniature X-band branch-line coupler using photoimageablethick-film materials

The design and measurement of a 10 GHz miniaturised branch-line coupler using thick-film photoimageable materials is presented. This attempts to reduce passive component size by demonstrating thin-film microstrip (TFMS)-based structures with a thick film processing technology. This technique offers a cheaper and faster way to implement compact multilayer circuits compared to thin-film technology. The fabricated hybrid of intrinsic area 1.19×1.07 mm demonstrates excellent performance and the measurements are in good agreement with the simulations