变容管电调微波带通滤波器

本文叙述采用梳状线结构的变容管电调微波带通滤波器的设计理论和方法。推导出梳状线带通滤波器的输入、输出耦合网络的参数条件,以补偿带通滤波器的谐振器之间电磁耦合随不同调谐频率的变化;并给出使带通滤波器的绝对带宽或通带回波损耗在调谐频率范围内变化最小时,梳状线谐振器的电长度应满足的相应条件,由此来保证电调带通滤波器在较宽的调谐频率范围内具有较高的通带回波损耗,且保持带通滤波器的响应形状和绝对带宽基本不变。此外,还讨论了由电调变容管的Q值引起的带通滤波器的通带有功损耗问题。文中给出了具体的设计公式。最后,给出了一个L波段变容管电调带通滤波器的研制实例和测试结果。     

频率可调带通-带阻可切换滤波器的设计

该文设计了一种频率可调带通与带阻可切换微带滤波器,在距λ/2(λ为波长)谐振器开路端约1/4处加载变容二极管实现中心频率可调,利用PIN二极管实现带通与带阻两种状态的可切换。通过对耦合系数与外部品质因数(Q)值的分析,选取合适的参数可实现滤波器绝对带宽在调谐范围内保持恒定。带通状态时,由于源与负载间的耦合及谐振器间的混合电磁耦合,在滤波器的通带两侧各产生1个传输零点,提高了滤波器的选择性与阻带抑制。选用介电常数2.2的F4BM介质基板制作实物并用矢量网络分析仪进行测量。测量结果表明,当PIN管加正偏压,变容二极管加反偏压时,实现了中心频率可调的带阻滤波器;当PIN管不加偏压,变容二极管加反偏压时,实现了中心频率可调的带通滤波器。滤波器的中心频率调谐范围为3.45～3.90 GHz,调谐范围内绝对带宽保持恒定。该滤波器尺寸为44.4 mm×16.1 mm(0.59λ_g×0.21λ_g)(λ_g为调谐范围中心频率对应波长),符合小型化要求。     

微波电压调谐微带环形谐振振荡器

研制出一种包含变容二极管可调谐微带环形谐振器的微波振荡器，该振荡器使用了单独封装的变容二极管和一些安装在环形结构内部的其它所需元件，通过变容二极管的正反向偏置，可实现约３０％的调谐带宽，测量发现，这一新的振荡器的相位噪声，偏离载波每ｋＨｚ优于一９０ｄＢｃ。     

基于交指结构的可调带通滤波器的设计

依据微带线的基本原理和电压调谐变容二极管的特性,结合微带交指滤波器的设计方法,提出一种基于交指结构的中心频率可调带通滤波器。设计了一种中心频率可调范围1.23～2.23GHz、带内插损小于4dB、带内平坦度优于0.5dB、相对带宽6.5%～4.5%的可调带通滤波器。经过ADS软件的仿真验证,证实了设计的有效性。     

基于枝节加载型SIR的可调滤波器

基于枝节加载型阶梯阻抗谐振器(SIR)设计了一种加载变容二极管的微带可调带通滤波器。SIR结构利于抑制高次谐波且可实现滤波器的小型化,提出的模型通过在SIR的中心平面加载2个枝节构成多模谐振器。通过奇偶模方法分析了枝节加载型SIR的谐振特性;通过加载变容二极管实现了对滤波器奇偶模谐振频率的独立控制,利用变容二极管容值的变化实现了滤波器的中心频率可调,中心频率随变容二极管偏置电压的增加而增大。该可调滤波器实现了在0.82~1.17 GHz范围内中心频率可调且插入损耗小于5 dB,回波损耗大于10 dB。     

新型折叠多模微带带通滤波器设计

文中提出了一种新型的小型化微带带通滤波器设计方案.方案所提微带带通滤波器的基本结构是折叠多模谐振器,该谐振器不仅具有谐振元件的特性,还能作为开路短截线.新型微带带通滤波器能够实现宽频带的通带响应,并在通带内具有较低的插入损耗和良好的阻带匹配特性,且在通带外额外产生了一对传输零点.本文给出了滤波器的等效电路分析和初步设计方案.该滤波器的最大优点在于进一步减小了滤波器尺寸,同时改善了滤波器的衰减极点,其中心频率为5.2 GHz.     

宽阻带三模谐振器微带带通滤波器设计

介绍了一种新颖的微带三模谐振器,由该谐振器构成的微带滤波器具有较宽的通带以及较好的带外抑制。对传统的单模微带环形谐振器结构进行优化,使谐振器在通带内具有三个谐振点,并且在通带边缘有四个对称衰减极点。引入的阶梯阻抗谐振单元使得微带三模谐振器具有良好的带外抑制。依据传输线原理对宽阻带三模谐振器进行了分析,并完成了中心频率为1090 MHz的宽阻带带通滤波器设计和加工,其实际测试结果与软件仿真结果具有良好的一致性。     

基于混合梳状线谐振器的三阶恒定带宽电调微带滤波器研究

文章提出了一种基于终端加载变容管的混合型梳状线谐振器的三阶电调微带带通滤波器,仅采用两个电压源进行控制．根据奇偶模分析方法,推导了混合梳状线谐振器间耦合系数计算公式,通过合理设计级间及输入输出耦合结构,绝对带宽保持恒定的要求可以得到满足．设计了一个调谐范围为1.0GHz～1.78GHz ,3dB绝对带宽为104.5±8MHz的三阶电调滤波器,其插入损耗小于5.7dB ,回波损耗优于16dB ,对二次谐波的抑制达到60dB ．实验结果表明,测试结果与电磁仿真结果基本一致．     

一种毫米波调谐微带滤波器的研制

该文基于金丝键合工艺和薄膜工艺,实现了一种低插损、小型化毫米波调谐微带滤波器。首先提出了一种加载矩形孔的半波长开路可调谐振器,通过在不同矩形孔上键合金丝来改变谐振器的等效电感值,从而改变谐振频率。然后利用所提出的可调谐振器实现了一种Ka频段五阶调谐带通滤波器,通过改变键合金丝状态来调谐频率,实现仿真和实测结果之间的偏差修正,解决了在毫米波频段由于介电常数批次性差异以及加工误差等因素造成的窄带滤波器频率偏移的问题。为了验证其可行性,对五阶调谐微带滤波器进行仿真、优化、加工及测试。结果表明,该滤波器的通带可调范围为35.35~35.95 GHz,插入损耗小于4.6 dB,能够实现所需通带。     

一种具有传输零点的Hairpin带通滤波器设计

本文通过在微带（hairpin）滤波器的谐振器上并联微带开路线，构成了一种新的hairpin带通滤波器。该滤波器在通带附近有一对传输零点，具有良好的频率响应以及频率选择特性。由于这种类型的微带滤波器实现传输零点不需要通过滤波器非相邻谐振器间的交叉耦合来获得，因此，设计过程非常简单。     

新型微带抽头式发夹型带通滤波器的设计*

利用ADS(Advanced Design System)软件设计、研究了一种新型的微带抽头式发夹型带通滤波器。该 滤波器工作在S 波段,相比较于传统的微带抽头式发夹型带通滤波器,该滤波器在信号的输入输出端各加入了一段 四分之一波长的开路微带线,很好地抑制了邻近的寄生通带,使滤波器具有了良好的阻带特性。同时在该滤波器的 谐振单元间并联了一段长度为λ / 2 的微带线,在该滤波器通带两侧增加了一对传输零点,使滤波器的选择性得到 了极大的优化。最后还对所设计的新型滤波器进行了实物加工和测试,测试结果和仿真结果吻合较好。     

Progress of a tunable active bandpass filter

A review of a tunable active bandpass filter developed in our research group is given here. Presented first is the basic structure of an end-coupled microstrip-line bandpass filter. Next discussed is the concept of using coupled negative resistance to compensate the loss of tank circuit. Then, the method of using varactor diode or mesfet varactor to tune the center frequency of the passband is discussed. The capability of optical-control of mesfet varactor and the concept of using mesfets as three-terminal varactors are also discussed.     

Hybrid Narrow-Band Tunable Bandpass Filter Based on Varactor Loaded Electromagnetic-Bandgap Coplanar Waveguides

A varactor-loaded resonator inserted between two Bragg reflectors has been implemented to design high-selectivity tunable bandpass filters. First, a mechanical tuning method is demonstrated. A varactor tunable bandpass filter is then implemented at 9 GHz, yielding good agreement between computational and experimental results. The tuning range reaches 3.5% with a loaded quality factor$Q_L =40$, a maximum insertion loss of 4.75 dB, and a return loss exceeding 20 dB. The theory is carefully explained, showing the importance of the parameters of the Bragg reflectors and of the resonator, in particular, the effect of diode-case parasitics and varactor position with respect to the resonator. A large-signal experimental analysis is done, showing a maximum allowable input power of a few dBm. Finally, possible filter improvements are discussed, and simulations with a microelectromechanical systems varactor are shown.     

硅基参数对微带带通滤波器传输特性的影响

随着半导体工艺技术和IC设计技术的飞速发展,硅基滤波器技术也不断更新换代。滤波器传输性能取决于基片介电常数、损耗和厚度等参数。研究了硅基不同厚度、损耗以及掺杂浓度等情况下,中心频率为5.75 GHz附近的平行耦合微带带通滤波器的传输系数和反射系数的频率响应特性。结果表明:当微带线带通滤波器PCB版图确定时,滤波器正向传输系数S21随着基片材料厚度的减小,通频带宽变窄;随着硅掺杂浓度的增加,通带向低频方向偏移;当正切损耗为0.000 4,0.004和0.04时,中心频率处S21分别为-14.18,-2.08和-0.81 dB。理论结果与实验数据进行比较,两者符合较好。     

Circularly polarized patch antenna with simultaneously wide frequency tuning range and high gain performance

A tunable circularly polarized square patch antenna with parasitic elements is designed for a wide frequency tuning range and high gain characteristics. The proposed antenna is constructed by one main patch and four semi-elliptic parasitic units. By loading four varactor diodes and adjusting their capacitance values, the tunable feature is performed to reallocate the corresponding working frequency. Moreover, the diagonal corners of the antenna are cut and loaded with varactor diodes, which provide the appropriate perturbation between the two orthogonality modes of the antenna, so as to ensure the circular polarization characteristic in the entire operating tuning band. The experimental results demonstrate that the reflection coefficient and axial ratio are less than −13 dB and 3 dB, respectively. The proposed antenna features a relatively wide continuously tuning range of 24% within 1.9-2.3 GHz and a stable gain of over 7 dBi with a radiation efficiency of above 85%.     

高选择性发夹型带通滤波器的设计

微带发夹型带通滤波器具有尺寸小、结构简单、性能稳定等优点,在射频微波领域有着广泛的应用。 本文使用ADS 软件设计仿真了一种高选择性抽头式发夹型带通滤波器。与一般发夹型滤波器相比,该滤波器在输 入输出端并联四分之一波长开路微带线,通过在寄生通带增加传输零点的方法提高滤波器的带外抑制性能。另外, 在该滤波器的谐振单元上增加并联阶跃阻抗枝节,在通带两侧产生一对传输零点,来提高该发夹型带通滤波器的选 择性。最后对这种高选择性发夹型带通滤波器进行实物加工,测试结果证实了该带通滤波器的良好选择性能。     

Electronically Tunable Microwave Bandpass Filters

Combline filters with novel input and output coupling networks which enable broad-band tuning to be achieved with minimum degradation in passband performance are discussed. Explicit design formulas for these filters are presented. Computer analysis of varactor tuned combine bandpass filters including the small signal varactor equivalent circuit is presented enabling filter performance to be easily evaluated. The design and experimental performance of a varactor tuned combline filter, realized in suspended substrate stripline is described. This filter toned from 3.2 GHz to 4.9 GHz exhibited low passband insertion loss and its performance was is close agreement with theoretical expectations.     

Variable Bandpass Filters Using Varactor Diodes

A rectangular waveguide type variable bandpass filter for the 4-GHz bandpass has been proposed and tested. The bandpass width varies from 260 MHz to 1.02 GHz for a filter using varactor diodes. Two microstrip variable bandpass filters for the 6-GHz and 4-GHz bands are also proposed and tested. The passband width varies from 310 MHz to1.24 GHz for a varactor-diode coupled filter, and it varies from 380 MHz to 2.18 GHz for a filter which is composed of low-pass and high pass filters connected in cascade. The center frequency of the three filters can be changed arbitrarily.