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。     

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。     

一种改进的一维周期DGS微带线

设计了一种新型一维周期缺陷接地结构（Defected Ground Structure，DGS）微带线。与周期均匀圆形缺陷的DGS不同的是，改进的周期DGS是一种补偿的微带线，圆形缺陷的尺寸是不均匀的，尺寸按照指数函数e^1/n（n为正整数）的相对振幅分布。文中设计了一个均匀周期DGS电路和两个改进的周期DGS电路，测量结果显示改进的周期DGS电路能够更好的抑制波纹和增大带阻带宽。     

1D非周期缺陷地结构微带线

针对50?微带线提出了新型一维非周期缺陷地结构(DGS)电路,不同于周期DGS,新型的DGS单元晶格是非周期的。设计、制造、测试了两个改进的缺陷地结构电路,测试结果表明该新型DGS可以产生通带和较宽的阻带。     

一种新颖的半圆形缺陷地结构微带线

本文提出了一种半圆缺陷地结构(Defected Ground Structure)微带线,该结构比传统的正方形DGS微带线有更好的带阻特性和等效Q值.本文分析了半圆DGS参数变化对带阻特性的影响,建立了该微带线的等效电路模型并提取参数;通过等效电路模型可以看出,半圆DGS微带线的Q值为45,大大优于传统DGS微带线的8.5.最后,本文设计了紧凑结构半圆DGS低通滤波器,由于半圆DGS微带线的高Q值,该滤波器的通带插入损耗小于0.2dB,其测试结果与仿真结果相当吻合,验证了所提结构的可靠性.     

基于DGS的紧凑型低通滤波器

文中提出一种基于缺陷地结构的新型低通滤波器。其由位于微带结构顶部的加宽微带线、位于接地层中的经典哑铃型缺陷地结构（DGS）和蛇形缝隙缺陷地结构（DGS）组成,结构设计紧凑,容易调整。文中选用0.01 dB等波纹的切比雪夫型低通滤波器,分别采用哑铃型DGS、蛇形缝隙DGS替换LPF原型电路中的电感,加宽微带线替换并联电容,同时将加宽微带线产生的寄生电感考虑进去。哑铃型DGS产生的高频衰减点加宽阻带,蛇形缝隙DGS提供的低频衰减点使得通带到阻带陡峭过渡。实验结果表明,所设计的截止频率为2.54 GHz的低通滤波器具有明显的截止频率响应,通带内插损均在0.9dB以下,阻带抑制均在21dB以下。经实物加工测试验证,所设计的低通滤波器实际结果与仿真结果基本一致,具有可行性。     

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。     

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。     

基于FDTD的DGS微带线特性分析

借助时域有限差分法（FDTD）并结合完全匹配层（PML）对多种类型的缺陷地结构（DGS）微带线进行了电磁仿真,分析了其带阻特性和慢波特性,并以哑铃型DGS微带线为例,分析了DGS结构参数改变对微带线带阻特性的影响。仿真结果与相关文献及HFSS软件仿真结果吻合良好,从而验证了该分析方法的有效性和计算的准确性。     

不同层面缺陷地对功率放大器的影响

论述了位于不同层面的缺陷地结构(DGS)应用于功率放大器的设计。一种是在微带线的两侧接地面刻蚀DGS,另一种是在微带线的背面接地刻蚀DGS,通过ADS Momentum仿真确定DGS的尺寸,并将这两种DGS应用到一款4 W功率放大器中进行仿真和实际制板测试。实测结果显示在微带线两侧接地面刻蚀DGS的功率放大器在输出功率为34.76 d Bm时改善二次谐波13 d B,且输出功率和功率附加效率(PAE)优于不刻蚀DGS的功率放大器。在微带线背面接地面刻蚀DGS的功率放大器在输出功率为34.21 d Bm时改善二次谐波28 d B,由于DGS结构改变了正面微带线的特征阻抗,所以输出功率和功率附加效率低于不刻蚀DGS的功率放大器。     

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.     

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.     

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     

Application of defected ground structure in reducing the size ofamplifiers

This letter presents a new technique to reduce the size of microwave amplifiers using a defected ground structure (DGS). The DGS on the ground plane of a microstrip line provides an additional effective inductive component, which enables a microstrip line with very high impedance to be realized and shows slow-wave characteristics. The resultant electrical length of the microstrip line with DGS is longer than that of a conventional line for the same physical length. Therefore, the microstrip line with DGS can be shortened in order to maintain the same electrical length, matching, and performances of the basic (original) amplifier. To confirm the validity of this idea, two amplifiers, one of which is designed using a conventional microstrip line and the other is reduced using DGS, are fabricated, measured, and compared. The performance of the reduced amplifier with DGS is quite similar to that of the basic amplifier, even though the series microstrip lines with DGS are much smaller than those of the basic amplifier by 53.8% and 55.6% at input and output matching networks, respectively     

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。     

A design of the low-pass filter using the novel microstrip defectedground structure

A new defected ground structure (DGS) for the microstrip line is proposed in this paper. The proposed DGS unit structure can provide the bandgap characteristic in some frequency bands with only one or more unit lattices. The equivalent circuit for the proposed defected ground unit structure is derived by means of three-dimensional field analysis methods. The equivalent-circuit parameters are extracted by using a simple circuit analysis method. By employing the extracted parameters and circuit analysis theory, the bandgap effect for the provided defected ground unit structure can be explained. By using the derived and extracted equivalent circuit and parameters, the low-pass filters are designed and implemented. The experimental results show excellent agreement with theoretical results and the validity of the modeling method for the proposed defected ground unit structure     

High isolation dual-polarized patch antenna using integrated defected ground structure

This letter presents a high isolation dual-frequency orthogonally polarized rectangular patch antenna utilizing microstrip feed line integrated with a defected ground structure (DGS). The demonstrated approach results in a significant improvement in port isolation in comparison to a conventional dual-polarized antenna fed by simple microstrip lines. Measurements show an improvement of 20 dB in port isolation relative to the conventional antenna, operating at 2 and 2.5 GHz. Image impedance of a microstrip line with DGS is controlled by the DGS geometry without modifying the dimension of the line. A 150 /spl Omega/ high impedance line is effectively implemented using a microstrip line with 75 /spl Omega/ line width by incorporating the DGS.     

Design of 10 dB 90° branch line coupler using microstrip linewith defected ground structure

The authors present a 10 dB 90° branch line coupler operating at 1.8 GHz and having a defected ground structure (DGS), a type of periodic structure realised by etching on the ground plane under the microstrip line. Owing to the additional effective inductance of the DGS, the characteristic impedance of the microstrip line is increased for the same width of conductor. A microstrip line of 150 Ω of characteristic impedance with 1 mm conductor width is realised by adding the DGS, while 1 mm corresponds to 82 Ω of conventional microstrip line on the RT/Duroid 5880 substrate with 2.2 dielectric constant and 31 mils of thickness. It is shown that a 90° branch-line 10 dB coupler can be fabricated using the 150 Ω line with DGS. Its measured performances are in good agreement with the predicted results