Ultra-Broadband Bandpass Filter Using Linearly Tapered Coupled-Microstrip Line and Open Loop Defected Ground Structure
Ultra-Broadband Bandpass Filter Using Linearly Tapered Coupled-Microstrip Line and Open Loop Defected Ground Structure
复制标题
使用线性锥形耦合微带线和开环缺陷接地结构的超宽带带通滤波器
DOI：
10.1109/tcsii.2020.3009415
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
R. Kshetrimayum
中科院分区：
文献类型：
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作者：
Ramanand Sagar Sangam;S. Dash;R. Kshetrimayum
提出了一种新型的基于线性渐变耦合微带线（LTC-ML）和开环缺陷接地结构（OL-DGS）的超宽带带通滤波器（BPF）。滤波器结构由具有开路短截线（OCS）的LTC-ML和蚀刻在地面上的OL-DGS组成。线性锥形和紧密耦合的微带OCS可以用作两个谐振器，并与OL-DGS相关联的增强耦合结构，它导致一个非常紧凑的三极滤波器。所提出的滤波器还表现出准椭圆函数响应，其中两个传输零点（TZ）更接近通带的每一侧，以提高选择性和一个TZ在较高的一侧的上阻带，可以观察到。一个近似的在线合成的建议三阶滤波器与三个TZs也已执行，这表明类似的特性，如所需的响应。该滤波器的仿真结果与实测结果吻合较好，在4.5 ~ 12 GHz范围内具有较宽的10 dB回波损耗带宽，插入损耗优于1.5dB，群时延变化小于0.2ns。此外，它在8.25 GHz的中心频率下具有非常紧凑的尺寸，为0.31g * 0.55g。
This brief presents a novel highly compact ultra-broadband bandpass filter (BPF) using linearly tapered coupled-microstrip line (LTC-ML) and open loop defected ground structure (OL-DGS). The filter structure consists of a LTC-ML with open-circuited stubs (OCSs) and an OL-DGS etched on the ground. The linearly tapered and tightly coupled microstrip OCS can function as two resonators, and with an associated enhanced coupling structure to OL-DGS, it leads to a very compact three-pole filter. The proposed filter also exhibits a quasi-elliptic function response, where two transmission zeros (TZ) closer to each side of the passband to improve selectivity and one TZ at higher side of the upper stopband, can be observed. An approximate in-line synthesis of the proposed third-order filter with three TZs has also been performed, which shows similar characteristics like the desired response. The simulated and measured results of the filter are in good agreement with each other, showing a wide 10 dB return loss (RL) bandwidth from 4.5 to 12 GHz, insertion loss better than 1.5 dB and group delay variation of lesser than 0.2 ns in the whole passband. Furthermore, it has a very compact size of $0.31\lambda _{g}\times 0.55\lambda _{g}$ at the central frequency of 8.25 GHz.