基于复合左右手传输线的双频不等分功分器

采用复合左右手(CRLH)传输线(TL)替代传统的四分之一波长阻抗变换器,设计了一种小型化且能同时工作在两个频率的不等分功率分配器(功分器),有效解决了传统功分器只能工作在指定的频率及其奇次谐波处的问题。通过理论分析,结合CAD软件进行仿真优化,设计了能同时工作于1 GHz和2.2 GHz,功率比为2的双频不等分功分器。理论和仿真结果显示,输入端匹配良好,并且两个输出端实现隔离。仿真结果和理论结果趋势吻合,验证了该方法的可行性。     

一种新型环谐振器在带通滤波器中的应用

本文设计了一种新型四分之一波长侧耦合线双模环形谐振器。根据滤波器的指标要求：中心频率、带宽、传输零点频率以及通带插八损耗,综合设计得出谐振器参数。将这种谐振器应用到传统的平行耦合微带线带通滤波器中,大大提高了滤波器的频率选择性。     

基于神经网络的耦合微带射频带通滤波器设计

给出了1/4波长耦合微带线射频带通滤波器设计的ADS仿真和神经网络方法.微带滤波器的3个重要参数线长L、线宽W、缝隙S以及频率freq做为神经网络的输入,反射系数S11和端口传输系数S21以及输入端电压驻波比VSWR1做为网络输出,神经网络训练结果和用电磁仿真软件ADS对滤波器的仿真结果基本一致.文中给出了采用改进粒子群优化(IPSO)算法思想改进的BP神经网络的训练算法.     

基于复合左右手传输线的带通滤波器小型化设计

提出了一种工作于X波段的基于复合左右手传输线理论的零阶谐振器单元.利用两个这样的零阶谐振器单元设计出一种工作于9.2 GHz～9.5 GHz的新型带通滤波器,对设计进行全波的仿真,并且将全波仿真结果和实验测量结果进行了对比.运用基于S参数的提取方法对该滤波器性能进行了理论分析.结果表明,该滤波器与基于耦合微带线形式的传...     

硅基BCB工艺X波段发夹型带通滤波器的实现

设计了发夹型微带线带通滤波器,并通过电磁仿真软件高频结构仿真器(HFSS)进行优化。以高阻硅为衬底,以大厚度低损耗因子的苯并环丁烯(BCB)为介质,通过MEMS加工技术制作了中心频率8. 6 GHz、带宽为9%的X波段带通滤波器样品。给出了详细的工艺流程,并就关键步骤进行介绍。给出了仿真结果与测试结果的对比,测试结果与仿真结果基本相符,制得的滤波器具有良好的传输性能,可以满足8. 2～9. 0 GHz频率范围内的通信要求,表明提出的设计方法合理,可实现工程应用。     

基于ADS的微带线带通滤波器的设计与优化

利用ADS(Advanced Design System)设计平行耦合微带线带通滤波器,为了缩短设计周期,提高微带线带通滤波器的性能,采用ADS中的无源电路设计向导工具,设计出了一种中心频率为3.0 GHz、带宽为60 MHz的平行耦合微带线带通滤波器。参数优化后进行电路版图仿真。仿真结果表明,该设计设计周期较短、方法切实可行,设计出的带通滤波器满足各项指标要求。     

正方形嵌套分形多频印刷对称振子天线

设计了一类具有正方形嵌套结构的新型分形多频对称振子天线.振子由一系列相似的正方形单元嵌套组成.天线能够同时工作于多个频率,这些频率涵盖了WLAN系统所要求的2.4 GHz/5.2 GHz/5.8 GHz三个频率,采用三维电磁仿真软件CST MWS(R)软件进行了仿真研究,得到了平衡微带线馈电的对称振子天线的模型.制作了...     

基于噪声消除技术的超宽带CMOS低噪声放大器设计

为满足3.5 GHz单载波超宽带无线接收机的射频需求,设计了一种工作在3～4 GHz的超宽带低噪声放大器。电路采用差分输入的CMOS共栅级结构,利用MOS管跨导实现宽带输入匹配,利用电容交叉耦合结构和噪声消除技术降低噪声系数,同时提高电压增益。分析了该电路的设计原理和噪声系数,并在基于SMIC 0.18μm CMOS射频工艺进行了设计仿真。仿真结果表明:在3～4GHz频段内,S11和S22均小于-10 dB,S21大于14dB,带内起伏小于0.5dB,噪声系数小于3dB;1.8V电源电压下,静态功耗7.8mW。满足超宽带无线接收机技术指标。     

一种新型高效宽带整流电路

提出一种新型高效宽带整流电路。通过在整流二极管前端串联一段微带线的方式,在其呈感性的范围内调节其长度,抵消二极管在基频上产生的容抗,使阻抗匹配时可以采用1/4波长阻抗变换方式取代单枝节匹配的方式,因而该整流电路的整体结构紧凑,同时拓展了工作带宽。改进直流滤波结构中的扇形枝节,根据其影响直流电压波形的现象调节其尺寸,使得输出直流电压纹波平稳,进一步提高整流效率。设计了一只5.8 GHz整流电路,测试表明,输入功率在0～16 dBm的范围内,该电路整流效率都在55%以上,最高效率达到78.7%;在13 dBm输入功率时,达到70%以上整流效率的相对带宽有16.6%。     

路基土壤含水量微波检测系统的设计研究

为实现路基土壤含水量测量设备精度高、持久性强、结构简单的需要,提出一种2.0GHz基于平行微带线结构的微波含水量传感器的设计方法.其测量原理基于土壤含水量与其相对介电常数之间线性关系,通过测量插入不同含水量土壤的微带线上正弦信号传输速率变化而产生的相位差,来求得含水量.研究工作实现平行微带线传感器系统的设计仿真,对含水量在0-30％范围内变化土壤样本测试,结果表明:测量分辨率≤0.1％,误差≤1％,系统响应时间≤1OOns,测量精度达到要求.这种新型微带线传感器体积小、功耗低、精度高、适合长期监测.     

Meander line MIMO antenna for 5.8 GHz WLAN application

A four port compact low profile planar MIMO antenna with meander line radiators and with polarization diversity effect has been proposed to cover 5.8 GHz wireless local area network application. The proposed MIMO antenna has ?10 dB impedance bandwidth of 1.4 GHz (5.3–6.7 GHz) along with the compact size of 38 × 38 mm² and an envelope correlation coefficient (ECC) of less than 4 × 10^?4 in the whole band. The proposed antenna resonates at 5.8 GHz frequency, having return loss of ?43.2 dB. The isolation between diagonal and opposite ports is more than 10 and 12 dB, respectively, in the presented frequency band. The total active reflection coefficient frequency response shows more than 1.0 GHz of bandwidth in the whole band. The antenna gain is more than 4.0 dBi in the operating frequency band. The radiating elements are very close to each other to make the design very compact.     

Design of novel compact anti-stiction and low insertion loss RF MEMS switch

A novel torsional RF MEMS capacitive switch design on silicon substrate is presented. The optimized switch topology such as reduction in up-state capacitance results in insertion loss better than ?0.1 dB till 20 GHz. Off to on state capacitance ratio is also improved by 18 fold and isolation is better than ?43 dB at 9.5 GHz. The achieved on state return loss is ?38 dB as compared to ?21 dB at 9.5 GHz. An optimized reduction in contact area and use of floating metal layer increases the switching speed from 56 to 46 μsec. It also increases the switch reliability by alleviating the stiction.     

A broadband coplanar waveguide to rectangular waveguide power divider using a slot

In this article, a broadband coplanar waveguide (CPW) to rectangular waveguide power divider using the dipole slot is proposed. The power divider consists of an input CPW port and two output rectangular waveguide ports. The CPW to rectangular waveguide power divider using the dipole slot has a return loss larger than 15 dB and an insertion loss equal to 3.08–3.27 dB in the whole X‐band (8.2–12.4 GHz). Furthermore, to broaden the bandwidth, the dipole slot is replaced by the bow‐tie slot. The CPW to rectangular waveguide power divider using the bow‐tie slot yields a return loss larger than 16 dB and an insertion loss equal to 3.05–3.29 dB from 8 to 13 GHz, which exceeds the X‐band. To verify our design, power dividers that use the dipole slot or the bow‐tie slot are fabricated and measured. The measurement results of both power dividers are in good agreement with the simulation results. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.     

Ultra‐wide stopband low‐pass filter using symmetrical cascaded modified hairpin resonators

An elliptical function low‐pass filter (LPF) with ultra wide stopband and sharp cutoff frequency is proposed. This filter is composed of symmetrical cascaded modified hairpin resonators and U‐shaped resonators. The transition band is from 1 to 1.21 GHz with ?3 and ?20 dB, respectively. For this filter, the return loss is better than 17 dB in 80% of passband width, where the insertion loss is less than 0.3 dB. The band‐stop rejection is greater than 20 dB from 1.21 to 26.35 GHz and 40 dB from 1.35 to 12.5 GHz. To validate the design and analysis, the proposed LPF has been designed and fabricated on a 20 mil thick RO4003 substrate with a relative dielectric constant 3.38 and loss tangent of 0.0021. The filter is evaluated by experiment and simulation with a good agreement. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:314–321, 2014.     

A dual‐feed MIMO antenna pair with one shared radiator and two isolated ports for fifth generation mobile communication band

In this article, a pair of unsymmetrical dual‐feed antennas with one shared radiator and two isolated ports is proposed for multiple‐input‐multiple‐output (MIMO) systems. The proposed antenna pair achieves high isolation between the two ports by properly adjusting the distance between the two feeding ports and the position and length of shorting strips on the radiator. The antenna has simple structure and covers the 3.3‐3.7 GHz band, which could meet the demand of future 5G applications. The measured results show that antenna has good impedance matching (better than 10 dB return loss) and high port isolation (better than 20 dB isolation) from 3.35 to 3.65 GHz. The total efficiencies are above 55% and the envelope correlation coefficient is <0.1, which is sufficient for MIMO applications.     

Wideband bandpass filtering branch‐line balun with high‐isolation

The wideband bandpass filtering branch‐line balun with high isolation is presented in this paper. The proposed balun can be designed for wideband performances by choosing a proper characteristics impedance of input vertical transmission line and odd‐mode impedance of parallel‐coupled lines. The proposed balun was designed at a center frequency (f₀) of 3.5 GHz for validation. The measured results are in good agreement with the simulations. The measured power divisions are ?3.31 dB and ?3.24 dB at f₀ and ?3 ± 0.17 dB within the bandwidth of 0.95 GHz (3 GHz to 3.95 GHz). The input return loss of 24.09 is measured at f₀ and higher than 20 dB over the same bandwidth. Moreover, the measured output losses are better than 11 dB within a wide bandwidth. The isolation between output ports is 20.32 dB at f₀ and higher than 13.2 dB for a broad bandwidth from 1 GHz to 10 GHz. The phase difference and magnitude imbalance between two output ports are 180° ± 4.5° and ± 0.95 dB, respectively, for the bandwidth of 0.95 GHz.     

Generalized high‐isolation n‐way Gysel power divider with arbitrary power ratio and different real terminated impedances

An exact closed‐form design approach for a generalized high‐power n‐way Gysel power divider is proposed. The power divider could be designed to achieve an arbitrary power ratio with the flexible multiway application, arbitrary real terminated impedance, excellent isolation, and easy fabrication through both planar and three‐dimensional structures. Moreover, this improved power divider could maintain high power processing capacity through the coaxial cavity transmission line and grounding resistances. The exact analytical solutions related to ideal port matching and high isolation are obtained based on the circuit and transmission‐line theory. To verify the proposed approach, a compact 3‐way coaxial power divider with a pre‐designed power ratio of 1:1.5:2 and four different real terminated impedances of 50, 55, 60, and 65 Ω is designed and fabricated. Excellent agreement is achieved between the simulated and measured results. Measurements from 4.7 to 5.7 GHz show that the return losses of all input and output ports are better than 15 dB. The maximum insertion loss is 0.5 dB, and the phase imbalance is approximately less than 6.1°. In addition, the isolation between any two output ports is better than 23 dB from 4.5 to 6 GHz. Meanwhile, the power handling capability can reach the maximum power of the commercial 50 Ω SMA connectors (2.098 kW).     

A low‐profile quad‐port UWB MIMO antenna using defected ground structure with dual notch‐band behavior

A compact (45 × 45 × 1.6 mm³) ultrawide‐band (UWB), multiple‐input multiple‐output (MIMO) design using microstrip line feeding is presented. The proposed design comprises four elliptical monopoles placed orthogonally on a cost‐effective FR‐4 substrate. In order to improve the impedance bandwidth and lessen the return loss of the MIMO antenna, defects in ground plane are created by etching symmetrical square slots and half‐rings. Moreover, a different method (of unsymmetrical H‐shaped slot with C‐shaped slot) was proposed into the patch to introduce dual‐band rejection performance from UWB at center frequency 5.5 GHz (covering lower WLAN as well as upper WLAN) and 7.5 GHz (X band). In addition, a stub is introduced at the edge of each defected ground structure to obtain isolation >–22 dB covering entire performing band from 2 to 16.8 GHz (where, S₁₁ < –10 dB). The proposed design has miniaturized size, very low envelop correlation coefficient less than 0.1, stable gain (2‐4 dBi except for notch bands). Furthermore, various MIMO performance parameters are within their specifications, such as diversity gain (= 10 dB), total active reflection coefficient (<–5 dB, and channel capacity loss (<0.35 bits/s/Hz). The presented design is optimized using the HFSS software, and fabricated design is tested using vector network analyzer. The experimental results are in good agreement with the simulation results.     

A low conversion loss single balanced subharmonic mixer

A new circuit topology for the design of a single balanced second‐order subharmonic mixer (SHM) is proposed. In the proposed topology, it is not necessary for the radio frequency (RF) and local oscillator (LO) signal to be within 15% frequency difference. Thus, the limitation of a conventional rat‐race mixer has been alleviated. Moreover, it shows very low conversion loss, high LO‐to‐RF, LO to intermediate frequency (IF), and 2LO‐to‐RF port isolations. The measured minimum down conversion loss is 5.8 dB at 13 GHz and remains below 7.65 dB over the 2 GHz RF operational band 12‐14 GHz for a fixed IF of 550 MHz. Measured LO‐to‐RF and LO‐to‐IF port isolations are better than ?40 dB over the entire operational band. The 2LO‐to‐RF isolation is more than ?62 dB which is extremely necessary for a second harmonic mixer where 2LO and RF frequency are close to each other. The input 1‐dB compression point is measured to be ?1 dBm.     

3GHz～5GHz CMOS超宽带低噪声放大器设计

提出了一个低噪声、高线性的超宽带低噪声放大器(UWB LNA).电路由窄带PCSNIM LNA拓扑结构和并联低Q负载结构组成,采用TSMC 0.18 μm RFCMOS工艺,并在其输入输出端引入了高阶带通滤波器.仿真结果表明,在1.8V直流电压下LNA的功耗约为10.6 mW.在3 GHz～5 GHz 的超宽带频段内,...