一种微带线到带状线宽带垂直耦合过渡结构

针对基于微波多层介质板的微带线到带状线过渡问题,提出了一种微带线到带状线宽带垂直耦合过渡结构,通过地层的圆形开孔完成微带线与带状线椭圆形贴片间的电磁耦合与匹配设计,实现了微波信号在微波多层介质板内跨层传输。将微带线到带状线宽带垂直耦合过渡结构在三维电磁场仿真软件中进行了建模,并对背对背结构进行了仿真、加工与测试。测试结果表明,在7~13 GHz的频带范围内输入输出回波损耗小于-12 dB,插入损耗最小为1.48 dB。该微带线到带状线宽带垂直耦合过渡结构具备了良好的性能,同时具有电路结构简单、加工方便等特点,在微波电路设计方面具有较高的实用价值。     

一种宽带微带线-悬置微带线过渡电路设计

基于悬置微带电路的应用需求,设计了一种新型的宽频带微带线-悬置微带线过渡电路,过渡结构采用"V型开槽地"结构实现微带线到悬置微带线电场方向的过渡转换,并使用渐变信号线进行阻抗匹配以拓展带宽。最终的仿真结果表明:该结构在0~40 GHz的频带范围内回波损耗优于15 dB,插入损耗小于0.165 dB,并且电路性能对电路尺寸的敏感性较低。该设计将具有超低损耗的悬置线与最常用的微带线电路相结合,并且具有宽频带、插损低、易于加工、结构紧凑等优势,改善了悬置微带电路的应用范围,可以更好地同其它电路或系统进行综合应用。     

基于厚薄膜混合基板的超宽带垂直互联设计

针对三维集成电路中基板层间信号垂直互联问题，基于厚薄膜基板的优良特性，设计了一种超宽带的同轴到带状线再到微带线的过渡结构，能够工作到80 GHz。这种垂直结构采用LTCC为基板，旋涂BCB膜层，适用于系统级封装。该结构利用“水滴”匹配的方法，并嵌入空气腔抑制寄生电容，有效地改善了互联结构的射频传输性能。仿真结果表明，其背靠背（同轴-带状线-微带线-带状线-同轴）结构在0～80 GHz频段范围内，回波损耗均低于-17 dB，插入损耗均优于-0.5 dB，驻波比均低于1.35，具有良好的超宽带传输特性。     

小型化双频印刷缝隙天线

针对无线通信系统中的多频段传输天线的小型化问题,设计了一种由L型微带线馈电的小型化缝隙天线。通过在地平面上开三个阶梯组成一端开口的缝隙切断电流路径,从而实现WLAN频段的双频带覆盖。运用电磁仿真软件对天线进行参数仿真和优化分析,通过改变缝隙的长度和宽度来实现天线同时工作在2.45GHz和5.8GHz。结果表明天线端口回波损耗S11≤-10dB以下工作带宽分别为2.4~2.49GHz和5.48~6.1GHz,满足IEEE802.11b/g和IEEE802.11a/n标准。同时对天线进行实物制作并进行端口回波损耗、增益和辐射方向图测试,仿真结果与测试结果比较吻合。相较于传统平面缝隙天线,本文提出的天线尺寸紧凑且结构简单,易于加工并与电路良好集成,具有广泛的通信应用前景。     

Ka波段波导-带状线转换结构

提出了一种Ka波段波导 带状线转换结构,通过在多层介质板上地层的椭圆形开孔与两个椭圆形金属贴片结构完成带状线与波导之间的电磁耦合与匹配设计,实现了Ka波段信号在波导与带状线之间的相互转换。同时将背靠背波导 带状线转换结构在三维电磁场仿真软件中进行了建模和优化仿真。经过加工与测试,结果表明,在32.3~38.3 GHz的频带内输入与输出回波损耗小于-10 dB,插入损耗小于1.2 dB。该Ka波段波导 带状线转换结构具备良好的性能,且具有结构简单、加工方便等优点,在毫米波电路设计方面具有较高的应用价值。     

高频板材的复介电常数测量方法研究

复介电常数是高频板材最重要的参数之一,准确测量高频板材的介电常数和损耗,对板材的实际应用十分重要。为了获得板材的损耗特性,设计了一种基于微带线的传输线电路,并对长度分别为25.4和127 mm的微带传输线进行仿真、加工和测试,得到DC-20GHz内的回波损耗S₁₁和插入损耗S₂₁,测试数据表明,S₁₁值测试结果在-15 dB以下,且在20 GHz下传输线的插入损耗为24.02 dB/m。通过加工误差分析,电路参数变化50μm时,DC-20GHz内仿真S_11max变化可达到6 dB左右。最后结合谐振环法对同一种板材进行测试,得到板材的相对介电常数和损耗角正切。结果表明该方法得到的损耗角正切精确度较高,且在2、10和20 GHz频段下误差小于10%。     

用于智能天线测试的低成本可调功分移相电路设计

为满足智能天线的波束赋形要求,设计一种用于微波暗室智能天线方向性测试的可调功分移相微带电路.该电路由Wilkinson功分器、π型电阻衰减器、加载线型移相器和同轴传输线级联而成.利用HFSS仿真软件优化设计了工作于TD-LTE的F频段功分比1∶2∶2∶1,依次相差105°的一分四电路结构,并进行了实物加工和测试.实测结果表明,电路输入输出驻波比均小于1.3,幅度误差小于0.6 dB,相位误差小于3..该电路结构制作成本低,幅相分配易于调整,满足测试应用需求.     

新型井下磁偶极子蛇形天线仿真设计

针对石油钻井井下天线工作在井筒钻井液及地层组成的特殊环境中,无线传输信号损耗大、难以可靠传输的问题,通过仿真建模,设计一种新型磁耦极子天线,具备高增益、抗干扰和小型化特点,实现井下无线数据的可靠传输。首先采用HFSS三维仿真软件构建仿真模型,详细将天线的长度、距离钻柱本体位置及天线的蛇形弯折数等关键参数进行计算,得出有效传输的参数组合和频点规律。据此规律,设计了天线实物,仿真结果与实物测试结果相比对,具有高度一致性,回波损耗可达到-7.5 dB以下,仿真设计的参数可以满足实际应用需求。该天线设计可应用于石油钻井井下无线传输,可提高信号发射强度,减小天线尺寸,降低系统功耗,实现无线信号可靠传输。     

一种太赫兹宽带三次谐波混频器设计与实现

提出了一种基于紧凑型过渡结构的低变频损耗太赫兹宽带三次谐波混频器。混频器中的紧凑型过渡结构,位于射频端波导内部,由电路正面的悬置带线和背面的三角形过渡段两部分组成,用于提高混频器的带宽,优化变频损耗。其中,悬置带线末端位于波导内射频信号电场的最大值处,正上方放置具有一对串联肖特基结的混频二极管,形成单平衡混频电路,使得射频信号仅与本振信号的奇次谐波混频,减少无效谐波分量。背面的三角形过渡段降低了悬置带线与射频波导之间的不连续性,有利于实现宽带匹配及混频电路小型化。混频器电路介质基板总尺寸为5.1 mm×6.9 mm×0.127 mm,实测结果表明,在135-165 GHz范围,混频器的单边带变频损耗为10.8-15.7 dB,典型值为13.0 dB,中频频率范围为0-15 GHz。     

基于 SRD 的二阶微分高斯脉冲发生器

基于阶跃恢复二极管（SRD）反向偏置时的阶跃恢复特性,设计了一种极窄的亚纳秒级二阶微分高斯脉冲发生器。该脉冲发生器主要由 SRD 串并联电路、RC 电路及并联微带线短路枝节组成,其中串并联结构的 SRD 用于形成窄脉冲,RC 电路用于信号的耦合及取代 SRD 的外偏置网络,微带短路枝节用于二阶脉冲的成形。利用 ADS对电路进行了仿真设计,并对电路进行加工制造,和串联或并联 SRD 脉冲发生器相比,串并联结构的输出电压明显提高,3V 纽扣电池供电时,实际测试的脉冲峰-峰值1.2V,脉冲宽度约600ps,脉冲对称性较好,振铃约-16dB。     

扇形短截线结构的椭圆微带低通滤波器设计

传统微带滤波器采用开路短截线形式,结构简单,易于设计,但是阻带衰减不够大,寄生通带抑制不充分,而且结构不紧凑。为了克服这些缺点,介绍了扇形短截线等效为电容和高阻抗微带线等效为电感的微带滤波器设计方法。并按此方法设计制作了1GHz椭圆微带低通滤波器。经过测试,该滤波器插入损耗小于1.5dB,阻带衰减60dB,阻带宽度超过通带3倍频以上,满足设计需求。结果表明,采用扇形短截线结构设计的微带滤波器,在物理尺度和滤波性能上比传统直短截线结构的微带滤波器更具优势。     

一款适用于5G通信频段的限幅滤波结构的设计

本文设计了一款新型的、工作于5G移动通信频段的限幅滤波一体化结构,其适用于射频前端,具有良好的电磁防护功能。该结构通过将限幅滤波两个模块进行一体化设计,避免了模块之间匹配网络的构建,实现了电路体积的减小。相较于传统的铁氧体频率选择限幅器,该结构在目标频段实现了宽跨度、大功率容量的特点。测试结果表明:在2.55~2.65 GHz频带内,该结构的插入损耗小于1.8 dB,限幅电平约为7.5 dBm;在4.8~4.9 GHz频带内,该结构的插入损耗小于2 dB,限幅电平约为2.5 dBm。在所选频带外,泄露功率被衰减到可忽略不计。因此,本文所设计的结构在保护敏感元件的同时可以有效提高射频前端接收机的灵敏度。     

宽频带的微带等角螺旋天线设计

为了实现宽频带天线指定方向的高性能辐射，设计了一种宽频带的微带等角螺旋天线。为实现阻抗匹配，天线馈电部分设计了一种指数渐变式微带巴伦结构。经过实物测试参数，结果表明加入了指数渐变巴伦结构后天线实现了良好的阻抗匹配并具有良好的宽频带特性，其工作带宽为1.74～4.82 GHz，回波损耗最低达- 30 dB。同时设计了一个平底型金属反射腔用于反射背向电磁波，在保持宽频带工作特性的同时，使天线具有了良好的单向辐射特性，天线在整个工作频段内的增益均大于6 dB，与传统的螺旋天线相比，具有宽频、定向、高增益的特点，具有一定应用前景。     

Evaluation of Chemical Solution Deposited Ba x Sr 1−x TiO 3 Thin Films on LaAlO 3 in Tunable Microwave Devices

Epitaxial Ba x Sr 1 m x TiO 3 (BST) films grown on LaAlO 3 by several deposition methods have been tested in coupled microstrip phase shifters (CMPS) at frequencies from 10 to 24 GHz. To date the best performance for the devices has been achieved using Pulsed Laser Deposition (PLD). However, recently chemical solution deposition (CSD) methods such as sol-gel and Metal-Organic Chemical Liquid Deposition (MOCLD) have shown advances in fabricating BST films for tunable microwave applications. CSD processes promise improvements in cost, speed and area covered during BST film deposition. This paper compares over 35 BST films used in identical CMPS circuits. In this study, the highest measured figures of merit of phase shift per dB of loss for PLD, MOCLD and sol-gel CMPS are 49, 47 and 41°/dB respectively. While other phase shifter designs using BST films have surpassed these values, these data base of identical circuits allows us to compare the BST films. X-ray diffraction characterization for many of the BST films is also given.     

Performance Enhancement of Tunable Bandpass Filters Using Selective Etched Ferroelectric Thin Films

The inclusion of voltage-tunable barium strontium titanate (BSTO) thin films into planar band pass filters offers tremendous potential to increase their versatility. The ability to tune the passband so as to correct for minor deviations in manufacturing tolerances, or to completely reconfigure the operating frequencies of a microwave communication system, are highly sought-after goals. However, use of ferroelectric films in these devices results in higher dielectric losses, which in turn increase the insertion loss and decrease the quality factors of the filters. This study explores the use of patterned ferroelectric layers to minimize dielectric losses without degrading tunability. Patterning the ferroelectric layers enables us to constrict the width of the ferroelectric layers between the coupled microstrip lines, and minimize losses due to ferroelectric layers. Coupled one-pole microstrip bandpass filters with fundamental resonaces at ～7.2 GHz and well-defined harmonic resonances at ～14.4 and ～21.6 GHz, were designed, simulated and tested. For one of the filters, experimental results verified that its center frequency was tunable by 528 MHz at a center frequency of 21.957 GHz, with insertion losses varying from 4.3 to 2.5 dB, at 0 and 3.5 V/ w m, respectively. These data demonstrate that the tuning-to-loss figure of merit of tunable microstrip filters can be greatly improved using patterned ferroelectric thin films as the tuning element, and tuning can be controlled by engineering the ferroelectric constriction in the coupled sections.     

Highly Textured Chemical Solution Deposited Ba 0.5 Sr 0.5 Ti 1−x Mn x O 3 (x ∼⃒ 0 to 5 at %) Thin Films For Microwave Dielectric Applications

We have optimized the process methodology to grow highly (100) oriented barium strontium titanate (Ba x Sr 1 m x TiO 3 ) (x = 0.5 and 0.6) thin films on lattice-matched (100) lanthanum aluminate (LAO) substrates by sol-gel technique. These films exhibited excellent phase shift and insertion loss characteristics at microwave frequencies. The work has been extended to study the effect of manganese (Mn) doping on the nature of epitaxial growth and electrical behavior of (100) oriented Ba 0.5 Sr 0.5 TiO 3 (BST) thin films. The degree of texturing and quality of the in-plane epitaxy of BST thin films on lanthanum aluminate (LAO) was found to be improved for upto 3 at% Mn doping. These films were characterized in terms of their electrical properties and dielectric behavior at low (1kHz-1MHz) and microwave frequencies. We have fabricated eight-element coupled microstrip phase shifters (CMPS) and tested them in terms of their degree of phase shift and insertion loss characteristics. The phase shift increases from 239 ° (undoped) to 337 ° with 3 at% Mn doping. However, the insertion loss also increases (5.4 to 9.9 dB respectively) with the increase in dopant concentration so that effective s factor (defined as phase shift/insertion loss) does not improve significantly and remains in the range of 33-44 °/dB. The observed electrical properties are correlated with the structure and microstructure of the Mn doped BST films.     

FABRICATION AND CHARACTERIZATION OF FULLY EMBEDDED DIPLEXER AND BAND-PASS FILTERS FOR ORGANIC RF SOP APPLICATIONS

ABSTRACT

In this paper, fully embedded dual-band WLAN diplexer, 2.4 GHz WLAN BPF and wide-band pass filter are investigated into a multi-layered organic package substrate for low cost RF SOP (System on Package) applications. These embedded passive components were designed and analyzed by using ADS circuit simulator and CST 3D EM simulator for verifying their applicability. The fabricated diplexer and filters are the smallest one of the filters formed onto the organic substrate. The diplexer has a size of 3 mm × 2.5 mm × 0.77 mm and exhibits an insertion loss of max ?0.68 dB in 2.4 ～ 2.5 GHz band and max –3 dB in 5.15 ～ 5.32 GHz band, respectively. The 2.4 GHz BPF has a size of 2.7 mm × 2.1 mm × 0.77 mm and exhibits an insertion loss of max ?2.7 dB. The WBPF has a size of 3.2 mm × 2.5 mm × 0.77 mm and exhibits an insertion loss of ?2.65 dB. The major benefit of these embedded passive components, compared to a discrete solution, is a significant simplification and size/volume reduction of RF systems design.     

Ka波段小型化自偏置微带环行器的设计与仿真

为了满足环行器小型化和集成化的需求,基于0.4 mm厚的锶六角铁氧体材料,采用多枝节短截线阻抗匹配设计,利用HFSS软件进行仿真,制备了工作在Ka波段的自偏置环行器。测试结果和仿真结果基本吻合。测试结果表明环行器工作在29 GHz附近,插入损耗3.4 dB,隔离度29.5 dB。分析了插入损耗的主要来源以及改进措施。