新型的平面双模椭圆函数带通滤波器

根据传统的方形贴片双模滤波器,提出了一种新颖的带有两个切角的平面双模带通滤波器结构.该结构使用单个贴片谐振器并且没有耦合缝隙,通带两端各有一个衰减极点,有效减小了滤波器的辐射损耗.对该滤波器结构进行改进,又提出了一种带有两个相互正交、长度不等槽线的双模椭圆函数带通滤波器结构.该滤波器在中心频率1.8GHz处,回波损耗达到31.53 dB,通带内最小插损达到0.01 dB,3 dB相对带宽为19.44%.采用Ansotf公司的En-sem ble 8.0仿真软件进行的仿真研究.仿真结果表明该结构可以更加有效地减小辐射损耗,增加带宽,且体积比传统滤波器减小了约40%,有利于小型化.     

新型微扰结构双模贴片带通滤波器设计

针对微带滤波器高性能小型化的需求,提出了一种方环形微扰单元的双模贴片带通滤波器的设计。该滤波器由方形贴片作为谐振器,输入、输出端口采用直接馈电,具有对称结构。利用在方形贴片上蚀刻出方环形缺口的方式,对方形贴片谐振器进行微扰,实现双模滤波器。通过电磁仿真软件Ansoft HFSS分析了微扰单元的特性,对双模滤波器的性能进行了仿真计算和优化。同时,也对该双模带通滤波器进行了实物加工和测量。实验结果表明,该滤波器的中心工作频率在3.32 GHz,相对带宽为6.9%,在通带的两侧各有一个传输零点,提高了阻带抑制,仿真与测量结果基本一致。     

单槽双频微波带通滤波器设计与实现

在方形贴片上采用单槽线代替相互正交双槽线的方法设计出一款结构简单、紧凑的双频段带通滤波器。详细讨论了滤波器结构参数对滤波器性能的影响,并以2.45/5.2GHz双通带滤波器的设计为例,通过仿真优化得到了各结构参数,制作了相应的样品。测试结果表明：该滤波器在2.45GHz通带内回波损耗为20dB,通带内最小插损为0.9dB,相对带宽为10%;5.2GHz通带内回波损耗33.6dB,通带内最小插损为0.37dB,相对带宽为13.4%,其总体尺寸比文献中正交双槽线结构的滤波器缩小48%。     

新型的方形贴片双模微带带通滤波器

提出了一种新型的方形贴片双模微带带通滤波器。该滤波器结构有一个切角,并且在贴片中心处开了一个两臂等长的十字槽,采用正交直接馈电方式,并在每条馈线上引入了一节与谐振腔有一定耦合的开路短截线。该结构在上下阻带都产生衰减极点,馈线上引入的微带线有效地抑制了寄生通带,提高了阻带抑制特性。仿真结果表明,该滤波器在中心频率2.9 GHz处,回波损耗优于–30.9 dB,通带内最小插入损耗为–0.1 dB,与实测结果基本一致。     

一种多模微带方形贴片带通滤波器的设计

提出了一种多模方式工作的微带方形贴片带通滤波器。通常设计微带方形贴片滤波器主要是利用TM1,0,0和TM0,1,0这一对简并主模实现单模或双模的工作方式。但是这些滤波器尚存一些有待完善的地方,诸如带内插损偏大,带宽受限等等。本文设计的带通滤波器不使用主模,而是利用三个高次模分量,通过一种简单的微扰方式和馈电方式激励起除简并主模以外的三个高次模分量,并使之相互耦合实现通带。仿真和测量结果充分说明,这种滤波器能够实现宽频段的通带响应,并且在通带内具有很低的插损和良好的阻抗匹配特性,能够广泛地适用于微波平面电路。     

基于微带贴片谐振器的高选择性双模双通带带通滤波器的研究

本文提出了基于微带贴片谐振器的高选择性双模双通带带通滤波器及一种模式分析算法.首次利用该算法分析了微带贴片的模式组成,计算了导模场的闭式解.微带贴片的耦合馈线同时作为谐振单元构成第二个通带,减小了结构尺寸.全波仿真分析（full wave analysis）结果及测试数据表明,与现有的双模双通带带通滤波器相比,本文设计的滤波器传输零点个数增加了2倍,达到11个,带外抑制度达到20dB,带内插损较小,仅为1.2dB,抑制了寄生通带.同时设计的拓扑结构复杂度较低,利于滤波器的小型化.     

低损耗双模微带贴片带通滤波器研究

首先提出了一种新颖、简单的带有两个切角的双模微带带通滤波器结构。该结构使用单个贴片谐振器并且没有耦合缝隙,通带两端各有一个衰减极点,可以有效减小滤波器的辐射损耗。对该滤波器结构进一步改进,又提出了一种中心频率1.8GHz相互正交槽线的新型双模微带带通滤波器结构。该滤波器在中心频率1.8GHz处,回波损耗达到31.65dB,通带内最小插损为0.01dB,3dB带宽为19.44%。研究结果表明该结构可以进一步减小辐射损耗,并且可以减小滤波器的体积,有利于小型化。     

十字形贴片双模微带带通滤波器

基于传统的贴片型双模微带带通滤波器,提出了一种结构新颖、简单的滤波器.该结构是在十字形贴片谐振器上刻蚀正交的T形槽通过中心处的方开槽相连.对该结构进行优化,优化后的滤波器能在通带两侧都产生衰减极点,提高阻带的抑制能力,同时保证滤波器的小型化.该滤波器仿真结果表明通带中心频率为2.75 GHz,最大回波损耗优于-32dB,通带内最小插入损耗为0.60dB,3dB带宽达到59.8％,实测和仿真结果相一致.     

基于频率选择表面的三通带太赫兹滤波器的设计与分析

目前三通带太赫兹滤波器存在通带带宽差异大的问题。为了提高太赫兹滤波器三通带的带宽均匀性，设计了一款基于频率选择表面的三通带太赫兹滤波器，其结构由三个嵌套式“十”字环金属贴片、“十”字金属贴片和聚酰亚胺衬底三层结构组成。当太赫兹波垂直入射到滤波器表面时，在0.1～0.862 THz范围内形成三个滤波通带，各通带的峰值透射系数约为0.9,具有较好的通带性能，并且通带之间的传输零点的透射系数都在0.07以下，带外抑制良好。各通带的3 dB带宽的最大通带比约为1.29,10 dB带宽的最大通带比约为1.13,具有较好通带均匀性。三个工作通带的矩形系数均大于1.7,通带边沿陡峭，频率选择性良好。该滤波器具有透射系数高、带宽差异小、结构简单和易于加工等特点，其在太赫兹的多信道通信领域具有广阔的应用前景。     

一种基于DGS结构的新型双模双通带滤波器

提出了一种新颖的基于缺陷地结构(DGS)的双模双通带滤波器.该滤波器由印制板顶面的一个方形谐振单元和另一个巧妙嵌入在印制板底面DGS中的方形谐振单元并联构成,具有结构紧凑、易于加工的特点.每个谐振单元都具有双模单通带传输特性,可通过公共馈线同时激励实现双模双通带滤波.两个谐振单元的谐振频率相对可调,提高了设计上的灵活性.为减少辐射损耗并改善高频通带插损,使用准共面波导缺陷地结构对底面谐振单元进行了改进.最后,实验制作了两种双模双通带滤波器,测试结果与仿真结果吻合较好.     

一种共面波导结构双模圆环带通滤波器

提出了一种新型的用共面波导馈线结构实现的双模圆环带通滤波器。该滤波器采用传统的圆环作为谐振器,引入阶梯阻抗作为微扰使其简并模式分离并产生耦合。这样的微扰结构我们称之为环形阶跃阻抗谐振器,它与输入/输出共面波导分别设计在介质基片的两个不同的面上。文中给出了该滤波器的结构及通过仿真和实验获得的性能参数,结果表明该滤波器在带宽为11.4%时通带内的最小插损为1.42dB。     

A novel coplanar-waveguide bandpass filter using a dual-mode square-ring resonator

A novel coplanar-waveguide (CPW) bandpass filter using a dual-mode resonator is presented in this letter. In the filter, a square-ring is used as the resonator, and a microstrip line stub attached the inner corner of the square-ring is used as the perturbation element. The square-ring and the input/output CPW are constructed on the two sides of a dielectric substrate, respectively. The filter has been investigated numerically and experimentally. Measured result shows that the filter has a minimum insertion loss of 1.2dB in its passband and an out-of-band rejection level of -45dB.     

A reduced-size dual-mode bandpass filter with capacitively loaded open-loop arms

A novel type of dual-mode microstrip bandpass filter using degenerate modes of a dual-mode microstrip square loop resonator with capacitively loaded open-loop arms is proposed. Such a dual-mode bandpass filter with a 0.75% bandwidth at the center frequency of 1.603 GHz is designed and fabricated to demonstrate the design of reduced-size microstrip filters. It is shown that the proposed filter has a size reduction of about 59% at the same center frequency, as compared with the dual-mode bandpass filters such as microstrip patch, cross-slotted patch, square loop and ring resonator filter.     

A novel dual-mode bandpass filter with wide stopband using the properties of microstrip open-loop resonator

A novel dual-mode microstrip square loop resonator is proposed using the slow-wave and dispersion features of the microstrip slow-wave open-loop resonator. It is shown that the designed and fabricated dual-mode microstrip filter has a wide stopband including the first spurious resonance frequency. Also, it has a size reduction of about 50% at the same center frequency, as compared with the dual-mode bandpass filters such as microstrip patch, cross-slotted patch, square loop, and ring resonator filter.     

Modeling of symmetric composite right/left-handed coplanar waveguides with applications to compact bandpass filters

This study proposes an equivalent-circuit model for the composite right/left-handed (CRLH) coplanar waveguide (CPW) comprising the series interdigital capacitor and shunt meandering short-circuited stub inductor in symmetric configuration. The new technique for extracting the equivalent-circuit elements of the CRLH CPW, which include inductances, capacitances, and resistances to represent the left-handed, right-handed, and lossy characteristics, is developed based on the effective medium concept. The applications to the compact resonators and filters are presented to emphasize the unique features of the CRLH CPW. A novel CRLH CPW resonator with a 0/spl deg/ effective electrical length at resonance is proposed, which gives a 49.1% size reduction when compared with the conventional half-wavelength resonator at 5 GHz. Based on the zeroth-order CRLH CPW resonators, an inductively coupled two-pole bandpass filter with 5.4% 3-dB bandwidth and 2.7-dB insertion loss at 5 GHz is implemented, and it is 51.4% more compact than the conventional structure. A good agreement among the results of the full-wave simulation, equivalent-circuit model, published data, and measurement demonstrates the effectiveness of the proposed modeling technique. To suppress the higher order harmonic spurious passbands, the electromagnetic-bandgap CPW structures are incorporated into the proposed CRLH CPW filter.     

Compact Millimeter-wave filters using distributed capacitively loaded CPW resonators

In this paper, a method for reducing the size of coplanar-waveguide (CPW) resonators, used in the design of compact bandpass filters, is presented. This is accomplished by incorporating a distributed array of capacitive loads along a resonant CPW line. Design of a miniaturized bandpass filter using capacitively loaded CPW resonators, which are inductively coupled, is presented. Inductively coupled bandpass filters with the proposed capacitively loaded CPW line resonators are designed and a size reduction of 25%, compared with filters using a standard CPW line resonator, is demonstrated. It is shown that, through this size reduction, the insertion loss is minimally increased (<0.4 dB). A hybrid algorithm, combining the method of moments (MOM) and circuit simulation is used to facilitate design process. Few filters using this technique are designed, fabricated, and measured at W-band. An excellent agreement between the simulation and measurement responses of these filters is presented.     

Coplanar waveguide-fed circularly polarized microstrip antenna

Design of a square microstrip antenna for obtaining circular polarization (CP) radiation using a coplanar waveguide (CPW) feed is presented. This CP design is achieved by insetting a slit to the boundary of the square microstrip patch, which makes possible the splitting of the dominant resonant mode into two near-degenerate orthogonal modes for CP radiation and introducing an inclined slot in the CPW feed line for coupling the electromagnetic (EM) energy of the CPW to the square patch. Good impedance matching for CP operation can be obtained by adjusting the inclined slot length and the tuning-stub length of the CPW feed line. Typical experimental results are presented and discussed     

Ultra-wideband bandpass filter with hybrid microstrip/CPW structure

A novel ultra-wideband (UWB) bandpass filter (BPF) is presented using the hybrid microstrip and coplanar waveguide (CPW) structure. A CPW nonuniform resonator or multiple-mode resonator (MMR) is constructed to produce its first three resonant modes occurring around the lower end, center, and higher end of the UWB band. Then, a microstrip/CPW surface-to-surface coupled line is formed and modeled to allocate the enhanced coupling peak around the center of this UWB band, i.e., 6.85GHz. As such, a five-pole UWB BPF is built up and realized with the passband covering the entire UWB band (3.1-10.6GHz). A predicted frequency response is finally verified by the experiment. In addition, the designed UWB filter, with a single resonator, only occupies one full-wavelength in length or 16.9mm.