一种新颖的微带线低通滤波器

针对传统微带线低通滤波器尺寸偏大、阻带较窄的问题,本文提出了一种新型结构滤波器.该滤波器由半圆型缺陷地结构(Semicircle Defected Ground Structure,S-DGS)单元和圆型阶梯阻抗并联枝节(Circle stepped-impedance shunt stubs,C-SISS)组成.文中首先分析了S-DGS和C-SISS结构对微带线低通滤波器带阻特性的影响,接着给出了微带线滤波器的等效电路模型.该滤波器3 dB截止频率为2.7 GHz,阻带为4～15.0 GHz,比传统DGS滤波器阻带拓宽了20%.测试结果与仿真结果吻合较好,验证了所设计滤波器的可靠性.     

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。     

Design and analysis of a structure-based microstrip bandpass filter

A structure-based microstrip passband filter with the center frequency of 2.6 GHz was put forward by using double-mode resonator based on defected ground structure （DGS） technology. A double-mode coupling resonator combined with DGS structure was used to achieve the resonance frequency and the filter size. CST microwave studio was used to optimize the attenuation performance to get the filter parameters. A structure-based passband filter was fabricated. Simulation is consistent with the measurement. Performance shows that the proposed filter could be suitable for the time division-long term devolution （TD-LTE） microwave systems at 2.6 GHz.     

基于嵌套缺陷地谐振器的紧凑型多通带滤波器*

根据双模缺陷地谐振器(DDGSR)在结构上易于嵌套实现多通带滤波器的独特优势,以及通过馈线中加上枝节线引入传输零点改善高频阻带特性的方法,提出了一种新颖的具有较陡边带和较宽高阻带特性的四通带滤波器。一节DDGSR 包含一个槽线谐振器(SLR)和一个缺陷地阶跃阻抗谐振器(DSIR),运用具有四节双模缺陷地谐振器的嵌套双模缺陷地谐振器结构,并通过仿真软件优化结构参数设计并制作了GPS(1.57GHz)、DCS(1.8GHz)、WLAN(2.4GHz)、WiMAX(3. 5GHz)频段的四通带滤波器。测试结果表明,四个通带中心频率分别为1. 58/1.8/2.42/3.58GHz,3dB 带宽为8.2/5/5.4/6.7%,带内插损最小值为1.2/1.6/1.6/2.6dB。设计与测试结果良好的一致性验证了理论的准确性。     

新型缺陷地结构改善射频功率放大器的性能

提出了一种新型的缺陷地结构,并将这种新型的缺陷地结构应用于实际所设计的射频功率放大器中.这种新型的缺陷地结构,蚀刻在射频功率放大器的偏置线下面的地平面和输出匹配电路后方的地平面,经过最后和不加这种结构的射频功率放大器进行比较和测试验证,证明成功的抑制了射频功率放大器的二次、三次谐波.     

Direct and electromagnetically coupled compact microstrip antenna design with modified fractal DGS

This article proposes ultra‐miniature microstrip patches with direct and electromagnetically coupled feeding mechanism for wireless communications at 10 GHz. Antenna size reduction is achieved here by loading a modified Minkowski fractal (type‐2) defected ground structure (MFDGS‐II) exactly beneath the radiating patch. The proposed method involves the selection of best DGS configuration through sensitivity analysis of the antenna structure. From different applications point of view, three different designs: a single layer direct fed patch and two electromagnetically coupled fed multi‐layered microstrip patch antennas are proposed here and designed with MFDGS‐II. The resonant frequencies of the antenna designs are reduced in a significant manner incorporating MFDGS‐II without any change in the physical size of the antenna. The prototypes of the proposed antennas are fabricated, and the performance parameters are measured. Compared with other existing structures, with a lower patch size of 0.20 λ₀ × 0.15 λ₀, the proposed single layered antenna with microstrip feed achieves a patch size reduction up to 67% and an overall volumetric reduction of 84%, respectively. Similarly, the proposed multi‐layered patch with proximity feed exhibits a maximum impedance bandwidth of 600 MHz and the aperture coupled fed patch has a realized gain of 6.2 dBi with radiation efficiency of 91% centered at 10 GHz. All three proposed compact antenna structures are best in three different aspects and have the potential to meet the practical requirements for X‐band portable wireless applications.     

一种新颖的开口环地面缺陷结构低通滤波器

提出了一种新颖的具有陡峭边带和宽阻带的小型化低通滤波器.通过把开口谐振环地面缺陷结构(Split-Ring Resonator Defected Ground Structure,SRR DGS)与阶梯阻抗梳状谐振器结合,提高了滤波器的选择特性,同时获得了宽阻带.对所提出的结构作了加工并进行了实物测量,测试结果表明:滤波器选择特性大于160 dB/GHz,在2.98 GHz到8.2 GHz范围内抑制度大于20 dB,而占用面积仅为20×25 mm~2.     

Three‐dimensional cylindrical design multiple‐input‐multiple‐output/diversity antenna with high isolation for wireless communication applications

In this article, a three‐port nonplanar multiple‐input‐multiple‐output/diversity antenna with very high isolation between the radiating elements is presented. To realize diversity from the proposed three‐dimensional (3‐D) antenna configuration, three monopole radiating elements are arranged at an angle of 120°. The isolation between the radiators is enhanced by using a multilayered cylindrical decoupling structure and defected ground structure (DGS). The DGS reduces the coupling due to surface waves while the cylindrical decoupling structure reduces the coupling due to space waves. The proposed antenna offers consistent pervasive connectivity in the wireless communication environment due to its 3‐D geometry with multiple radiating elements and good diversity performance. The prototype is fabricated and measured result shows that more than 42 dB isolation is obtained at the center frequency 1.45 GHz. An increment of 1.2 dBi in the antenna gain is also achieved by using DGS and decoupling structure arrangement. The proposed antenna can be easily placed inside the cylindrical housing or it can be integrated with the existing electronics chip, thus nullifying the requirement for dedicated location in the system.     

Comparative performance of some polynomial-based lowpass filters for microwave/digital transmission applications

This paper reports on the comparative performances of some polynomial based lowpass filters in the lumped elements, microstrip and defected ground structure (DGS) environment. The microwave designers are normally familiar with Butterworth, Chebyshev and Bessel filters. However, many more polynomials based, ripple and non-ripple types LPF have been suggested for the low-frequency applications. Some of these LPF, such as L-opt, H-type, Transitional Butterworth-Legendre (TBL), Pascal, Legendre group of LPF, are compared for their applications in analog microwaves, digital transmission, efficiency enhancement of the linear power amplifiers and five level partial response modulations. A method is reported to compute the ripple frequency for the Legendre group of LPF and Pascal LPF. Further, a design is suggested to significantly improve group delay performance of high selectivity filters.