A design of the novel coupled-line bandpass filter using defectedground structure with wide stopband performance

In this paper, a novel three-pole coupled-line bandpass filter with a microstrip configuration is presented. Presented bandpass filters use defected ground structure (DGS) sections to simultaneously realize a resonator and an inverter. The proposed coupled-line bandpass filter provides compact size with low insertion-loss characteristic. Furthermore, a DGS shape for a microstrip line is newly proposed. The proposed DGS unit structure has a resonance characteristic in some frequency band. The proposed coupled-line filter can provide attenuation poles for wide stopband characteristic due to resonance characteristic of DGS. The equivalent circuit for the proposed DGS unit section is described. The equivalent-circuit parameters for DGS are extracted by using a three-dimensional finite-element-method calculation and simple circuit analysis method. A design method for the proposed coupled-line filter is derived based on coupled-line filter theory and the equivalent circuit of the DGS. The experimental results show excellent agreements with theoretical simulation results     

Compact asymmetric coplanar waveguide filter

The design and implementation of a novel asymmetric coplanar waveguide (ACPW) band rejection filter using defected ground structure (DGS) is presented. The proposed ACPW DGS technology provides bandgap characteristics with only one cell in the lateral ground plane. The equivalent circuit model of the proposed DGS unit section is described. Measurements of ACPW DGS showed good agreement with simulation and the proposed model.     

一种新颖的蝴蝶结形缺陷接地结构微带线

提出一种新颖的蝴蝶结形缺陷接地结构(DGS)微带线,分析了该微带线的带阻特性和慢波特性,同时考虑微带线损耗,建立了该微带线的等效电路模型及其参数提取,并分析了蝴蝶结形DGS结构变化对阻带特性的影响,最后将该DGS结构应用于紧凑结构低通滤波器的设计,模拟结果与实验结果吻合较好,验证了所提结构的可靠性。     

微带DGS低通滤波器的设计

研究了实现DGS(defected ground structure)低通滤波器的方法。DGS滤波器具有很好的慢波、带阻特性,可以有效地改善滤波器特性。利用电路分析法讨论了DGS微带线的等效LC电路及其参数提取。研究了加窗技术在微带缺陷地结构中的应用,仿真表明加窗技术可以有效地改善带内平坦度。制作了相应的实际电路,仿真结果和实验测试结果基本吻合。     

Quasi-elliptic filter characteristics of an asymmetric defected ground structure

An asymmetric defected ground structure (DGS) with respect to a microstrip line is proposed. Its unit cell consists of two square slots connected with a rectangular slot by meandered transverse slots. The simulated, measured and equivalent circuit responses have been presented. The unit DGS pattern under microstrip line produces wide rejection bandwidth and high sharpness factor. Its elliptic band-reject filter response is modelled by appropriate LC equivalent circuit. Two such DGS cells under a microstrip line produce 3-pole quasi-elliptic bandstop filter response, which shows deeper attenuation without appreciable change in pole frequencies in comparison to single cell structure. Unit DGS pattern under coupled gap microstrip lines produces band-accept filtering characteristics. The frequency characteristics show a quasi-elliptic highpass filtering characteristics with sharp lower transition knee. Accordingly, an LC equivalent circuit is proposed. A cascaded band-accept and band-reject filter is proposed for designing a wideband bandpass filter. The bandwidth and centre frequency of the bandpass filter can be varied by choosing different set of DGS dimensions.     

C型环缺陷地结构带阻滤波器

为了进一步提高微波滤波器的品质性能,增强其应用性,提出了一种新型的C型环缺陷地结构(DGS-Defected Ground Structure)单元,该单元几何图形简单,可减小滤波器尺寸。经过对C型环DGS单元带阻特性的分析仿真,得到了最佳性能的仿真模型。实验结果表明,C型环缺陷地结构单元可获得极窄的阻带(约1GHz),由C型环单元构成的滤波器Q值可达130.2。     

DGS Dual Composite Right/LeftHanded Transmission Line

The planar dual composite right/left-handed transmission line (D-CRLH TL) using a defected ground structure (DGS) and stub with rectangular patch is presented. The required series parallel resonance tank and shunt series resonance tank for the D-CRLH TL are provided by DGS and stub with rectangular patch, respectively. Its equivalent circuit is provided to analyze D-CRLH TL. The characteristics such as dispersion relation and frequency response of D-CRLH TL are analyzed by circuit analysis, Bloch-Floquet theory, and full wave simulation. The measured results of dispersion curves and frequency behaviors have good agreements with theory. Finally, it is shown that compact multiband resonator using proposed D-CRLH TL can be realized.     

An asymmetric defected ground structure with elliptical response and its application as a lowpass filter

A new asymmetric defected ground structure (DGS) consisting of two square headed slots connected with a rectangular slot transversely under a microstrip line is proposed. In the frequency characteristics of its unit cell, an attenuation zero is observed close to the attenuation pole. The DGS unit is represented by Cauer's T-network, modeled by a third order elliptical lowpass filter and finally equivalent L-C parameters are extracted. Several studies have been accomplished on the influence of the geometric modification of the filter on its characteristics. Better transition sharpness, lower passband insertion loss and broader stopband are observed, compared to popular dumbbell DGSs due to its additional attenuation zero. The two-cell configuration of this DGS produces a three-pole lowpass filter having wide and deep stopband at low cutoff frequency. This is applied under the input and output feed lines of a parallel-coupled bandpass filter for suppressing harmonic frequencies. A lowpass filter is realized using cascaded investigated DGS and dumbbell DGS under a microstrip line.     

基于缺陷地面结构和补偿微带线的低通滤波器

提出了一种新型一维周期缺陷地面结构（DGS）单元。文中给出了3个不同尺寸单元的5参数变化曲线,并使用DGS单元进行级联,形成一种补偿微带线。设计了一个低通滤波器,计算和测试结果显示该结构单元的截止频率由结构单元的物理尺寸决定,单元级联形成的多级低通滤波器具有良好的带通、带阻和谐波抑制特性。     

Miniaturized microstrip lowpass filter with wide stopband using double equilateral U-shaped defected ground structure

A compact double equilateral U-shaped defected ground structure (DGS) unit is proposed. In contrast to a single finite attenuation pole characteristic offered by the conventional dumbbell DGS, the proposed DGS unit provides dual finite attenuation poles that can be independently controlled by the DGS lengths. A 2.4-GHz microstrip lowpass filter using five cascaded double U-shaped DGS units is designed and compared with conventional DGS lowpass filters. This low pass filter achieves a wide stopband with overall 30-dB attenuation up-to10 GHz and more than 42% size diminution.     

A novel defected ground structure for an active device mounting and its application to a microwave oscillator

This letter is to present a new defected ground structure (DGS), which is useful for mounting an active device, and its application to a microwave oscillator. The newly proposed DGS circuit is useful for mounting a transistor such as a BJT or field effect transistor (FET) on ground plane. In order to bias dc to a transistor, it is necessary to implement the dc isolated circuit in a practically applied active device with a DGS. For dc isolation, each branch of DGS should be isolated from ground. However, the proposed DGS structure with dc isolations introduces a degradation of gain performance for a transistor and changes the matching point. In order to overcome these limits, we have investigated a coupling method by using the simple coupling capacitor without degradations in RF performances. This letter displays the comparison of several measurements for the fabricated DGS circuits including the case that compensates the degradations due to the dc isolation. Furthermore, a design example of a microwave oscillator with the proposed DGS is demonstrated to show the validity of this letter.     

Design of a wideband common-mode filter using approximate closed-loop pattern of compact C-shaped defected ground structure

A compact common-mode filter is proposed to suppress common-mode noise for application of high-speed differential signal traces. The filter adopts one big C-shaped defected ground structure (DGS) cell in the left of ground plane and two small C-shaped DGS cells with opposite direction in the right of ground plane. Because these DGS cells have different dimensions, the filter has three adjacent equivalent resonant points, which can suppress wideband common-mode noise effectively. The left C-shaped DGS and its adjacent C-shaped DGS cell form an approximate closed structure, which can efficiently reduce the influence of the mutual capacitance. The filter provides a common-mode suppression from 3.6 GHz to 14.4 GHz over 15 dB while it has a small size of 10 mm10 mm. The fractional bandwidth of the filter is 120%, and the differential signals still keep good signal integrity. The experimental results are in good agreement with the simulated results.     

一种新型一维周期DGS单元结构特性研究

该文设计了一种新型一维周期地面缺陷(Defected Ground Structure, DGS)单元结构,该DGS单元结构提高了等效电感。增加的等效电感可以容易控制DGS平面电路的截止频率特性。设计的周期DGS单元结构有非常好的截止和带阻特性。为了显示改进的等效电感,该文设计了3个周期相同而单元尺寸不同的DGS电路。DGS电路的测试结果显示截止和带阻的中心频率特性由该DGS单元结构的物理尺寸决定。     

基于CQ拓扑的三通带滤波器的设计

提出和设计了一个三通带带通滤波器,采用CQ拓扑和缺陷地结构,产生了8个传输零点,获得了高频率选择和带间隔离。半波长阶梯阻抗谐振器(SIR)设计为同时谐振在第1、2和3通带的公共谐振器,公共谐振器和分别谐振在第1、3通带的1/4波长谐振器(QWR)组合构成CQ拓扑结构。同时,阴刻在地表面的缺陷地结构提高了调节耦合系数的自由度,便于调节耦合系数来满足特定要求。设计、加工和测量了工作在2.4GHz、3.4GHz和5.5GHz的三通带滤波器,测试结果和仿真结果的一致性证明了提出的设计方法的可靠性。     

Harmonic suppression with photonic bandgap and defected ground structure for a microstrip patch antenna

This letter presents a microstrip patch antenna integrated with two-dimensional photonic bandgap (PBG) and one-dimensional defected ground structure (DGS) jointly in ground plane. It is demonstrated that application of both PBG and DGS eliminates the second and third harmonics and improves the return loss level. Moreover, the combination use of PBG and DGS decreases the occupied area by 70% compared to the conventional PBG patch antenna.     

神经网络在微带DGS结构设计中的应用

采用神经网络对微带DGS结构进行建模分析。由于神经网络具有精度高、实时调用速度快等优点，因此本文所介绍的对DGS结构的神经网络设计方法可替代通常所使用的FDTD分析方法，作为电路设计辅助工具。仿真结果证明了该方法的有效性。     

神经网络在微带DGS结构设计中的应用

采用神经网络并结合逆向方法训练网络对微带DGS(Defected Ground Structure)结构进行建模分析。通过文中实例可以看出,人工神经网络产生的结果与数值仿真的结果吻合良好,证明该方法结合FDTD分析方法,作为电路设计辅助工具,具有缩短设计时间、降低设计成本的优点。为微带DGS结构分析和设计提供了一个新途径。     

Dual-band bandpass filter based on dual-plane microstrip/interdigital DGS slot structure

A novel dual-band bandpass filter based on a dual-plane structure consisting of both a microstrip and a defected ground structure (DGS) slot with an interdigital shape is proposed. The microstrip structure is connected to the ground plane by grounding vias to obtain tight coupling. By tuning the length of the fingers in the DGS, it is convenient to change the first passband operating frequency. The equivalent-circuit model is derived for the filter. A filter with two passbands centring at 2.44 and 3.28 GHz is shown with stopband attenuation of greater than 30 dB over the frequency range 3.7- 9 GHz.     

一种按照指数函数相对振幅分布的新型周期DGS微带线设计

设计了一种新型一维周期接地缺陷结构(DGS)微带线。与传统的周期均匀DGS单元微带线不同的是,这种改进的周期DGS平面电路是一种补偿的微带线,每个DGS单元尺寸是不同的,尺寸按照指数函数e1/n(n为正整数)的相对振幅变化。本文设计了一个均匀周期DGS平面电路和两个改进的周期DGS平面电路,测量结果显示改进的周期DGS平面电路能够更好地抑制波纹和增大带阻带宽。     

周期性缺陷接地结构的BP神经网络模型

缺陷接地结构 (DGS)是由光子带隙结构 (PBG)发展而来的 ,它是在微波电路的接地金属平面上人为地蚀刻出“缺陷”,改变接地电流的分布 ,从而改变传输线的频率特性。周期性缺陷接地结构 (PDGS)是一种在微波电路的接地金属平面上人为地蚀刻出周期性的“缺陷”结构 ,能够使某些频段的电磁波无法从中通过 ,存在明显的阻带特性。文中采用人工神经网络对周期性缺陷接地结构进行建模 ,将其结构尺寸和频率作为输入样本 ,传输系数参数作为输出样本 ,采用贝叶斯正则化算法对神经网络进行训练。神经网络训练完成后 ,在学习范围内将其结构尺寸和频率输入到神经网络模型 ,从输出端立即得到准确的传输系数。