Compact UWB Bandpass Filter Using Stub-Loaded Multiple-Mode Resonator

A compact microstrip-line ultra-wideband (UWB) bandpass filter (BPF) using the proposed stub-loaded multiple-mode resonator (MMR) is presented. This MMR is formed by loading three open-ended stubs in shunt to a simple stepped-impedance resonator in center and two symmetrical locations, respectively. By properly adjusting the lengths of these stubs, the first four resonant modes of this MMR can be evenly allocated within the 3.1-to-10.6 GHz UWB band while the fifth resonant frequency is raised above 15.0GHz. It results in the formulation of a novel UWB BPF with compact-size and widened upper-stopband by incorporating this MMR with two interdigital parallel-coupled feed lines. Simulated and measured results are found in good agreement with each other, showing improved UWB bandpass behaviors with the insertion loss lower than 0.8dB, return loss higher than 14.3dB, and maximum group delay variation less than 0.64ns in the realized UWB passband     

Compact UWB Bandpass Filter With Improved Upper-Stopband Performance

In this letter, a novel ultra-wideband (UWB) bandpass filter with compact size and improved upper-stopband performance has been studied and implemented using multiple-mode resonator (MMR). The MMR is formed by attaching three pairs of circular impedance-stepped stubs in shunt to a high impedance microstrip line. By simply adjusting the radius of the circles of the stubs, the resonant modes of the MMR can be roughly allocated within the 3.1-10.6 GHz UWB band while suppressing the spurious harmonics in the upper-stopband. In order to enhance the coupling degree, two interdigital coupled-lines are used in the input and output sides. Thus, a predicted UWB passband is realized. Meanwhile, the insertion loss is higher than 30.0 dB in the upper-stopband from 12.1 to 27.8 GHz. Finally, the filter is successfully designed and fabricated. The EM-simulated and the measured results are presented in this work where excellent agreement between them is obtained.     

Ultra wideband bandpass filter with dual-notched bands using stub-loaded rectangular ring multi-mode resonator

This paper presents a new ultra wideband (UWB) bandpass filter (BPF) with dual-notched bands (at 5.2/5.7 GHz) using the stub-loaded rectangular ring multi-mode resonator (MMR). The proposed resonator consists of the dual embedded open-circuited stubs for introducing the dual notch bands and connected with a stub-loaded rectangular ring structure for controlling the two transmission zeros (at 3/11 GHz) at both sides of the UWB passband edge. This study mainly provides a simple method to design a UWB bandpass filter with high passband selectivity and dual-notched bands for satisfying the Federal Communications Commission (FCC-defined) indoor UWB specification. Experimental verification is provided and good agreement has been found between simulation and measurement.     

一种新型超宽带小型化U型微带滤波器

提出了一种新型超宽带(UWB)小型化微带滤波器。这种结构采用多个短路支节并联于主传输线上,短路支节长度为四分之一波长。采用一种新型等效电路对其进行分析、模拟,其中的主传输线、并联支节线以及T型结、拐角、接地孔等不连续处均等效为相应的电路元件,并结合适当的U型电路变形。通过精确建模、仿真,使这种新型结构的滤波器具有更小的体积和更宽的通带。采用0.762 mm厚RT Duriod 6002板材实际制作一个通带为3～21 GHz的超宽带微带滤波器,尺寸为12 mm×21 mm×0.762 mm。该滤波器不仅体积小,且性能优良,其带内损耗小于2.1 dB,回波损耗优于-8.2 dB。实做通带2.96～21.01 GHz,带宽达150.6%,与仿真结果较为吻合,可以满足工程应用的需要。     

EBG-Embedded Multiple-Mode Resonator for UWB Bandpass Filter With Improved Upper-Stopband Performance

An electromagnetic bandgap (EBG) embedded multiple-mode resonator (MMR) is proposed to constitute an upper-stopband-improved and size-miniaturized ultra-wideband (UWB) bandpass filter (BPF). This EBG-embedded MMR is studied to relocate its first three resonant modes within the 3.1-10.6GHz passband, whereas placing its 4th resonant mode at the coupling transmission zero of interdigital coupled-lines that drive this MMR at two sides. Meanwhile, the fifth resonant mode is rejected by virtue of the bandstop behavior of the EBG itself. Thus, a modified UWB BPF with widened upper-stopband, sharpened upper rejection skirt and lowered loss in the passband is finally constituted, designed and fabricated. The measured results demonstrate that the insertion loss is lower than 1.0 dB in the passband (4.0-10.6GHz) and higher than 15.0dB in the upper-stopband (12.0 to 20.0GHz) while the group delay variation in the passband is less than 0.2ns     

Compact Ultra-Wideband Bandpass Filter Using Dual-Line Coupling Structure

This letter presents a novel compact ultra-wideband (UWB) microstrip bandpass filter with spurious response suppression. A dual-mode ring resonator is constituted to allocate its first two resonant frequencies in the UWB band, and the dual-line parallel-coupled structure is used in this compact UWB filter, which is expected to achieve much tighter coupling degree. Simulated and measured results are found in good agreement with each other, showing a wide passband from 4.9 to 10.9 GHz, 15 dB return loss bandwidth of about 5 GHz, minimum insertion loss of 0.49 dB at 7.3 GHz, and wide upper stopband with more than 20 dB attenuation up to 20 GHz.     

Ultra-Wideband Bandpass Filter Using Multilayer Liquid-Crystal-Polymer Technology

Novel ultra-wideband (UWB) bandpass filters are proposed based on quasi-lumped-element prototypes and implemented with multilayer liquid-crystal-polymer (LCP) technology. In this study, the broadside-coupled microstrip radial stubs and high-impedance microstrip lines are adopted as quasi-lumped elements for realizing compact UWB bandpass filters. By introducing a short-circuited high-impedance microstrip line as a shunt inductor and suitably designing quasi-lumped-element capacitors, a compact six-pole bandpass filter is implemented with the Federal Communications Commission (FCC) defined UWB specifications. To further improve the selectivity and wideband performance, an eight-pole filter of this type is developed by adding two shunt short-circuited microstrip stubs, which introduce a transmission zero at the upper passband edge. The proposed filters are fabricated using multilayer LCP technology. Good agreement between simulated and measured results of these filters are observed. The measured results show that the fabricated six-pole filter has good specifications for the FCC-defined UWB system. The fabricated eight-pole filter has an ultra-wide fractional bandwidth (139%) and a good stopband rejection level, which is higher than 38.1 dB from 10.57 to 18.0 GHz. The proposed filters are attractive for UWB communications and radar systems.      

基于E型谐振器的三陷波超宽带带通滤波器

针对超宽带系统中存在窄带信号干扰的问题,提出了一种加载E型谐振器的多模谐振器(Multimode Resonator,MMR)结构,采用内嵌开路枝节的方法设计了一款三陷波超宽带滤波器,并且通过调节内嵌开路枝节的长短,实现了双陷波的性能。该超宽带带通滤波器通带频带范围为3. 1~10. 2 GHz,通带内插入损耗小于1 d B,相对带宽为107%。其中,实现的三陷波滤波器的三个陷波中心频率分别为3. 8,5. 1和6. 6 GHz。通过调节内嵌开路枝节的长短,可以实现双陷波到三陷波之间的转换,仿真结果与理论分析一致。     

基于方开环谐振器的双陷波超宽带滤波器

针对超宽带系统易受窄带信号干扰的问题,设计了一种可以抑制无线局域网络(WLAN)和卫星通信信号干扰的双陷波超宽带带通滤波器。该滤波器的主要谐振结构由T型枝节加载的多模谐振器组成,改进的T型枝节增加了两个传输零点,同时减小了滤波器尺寸;通过耦合方开环谐振器,实现了两个陷波特性,调节谐振器尺寸,可以得到所需的陷波频率。测试结果表明,该滤波器的尺寸仅16.7mm×8.5mm,中心频率为6.9GHz,通带为3.0~10.8GHz,陷波中心频率在5.8GHz和8.04GHz,衰减最低点分别为-27dB和-18dB,仿真与测量结果有较好的一致性。     

Capacitive-Ended Interdigital Coupled Lines for UWB Bandpass Filters With Improved Out-of-Band Performances

This letter presents a novel ultra-wideband (UWB) microstrip bandpass filter on a microstrip line with improved out-of-band performances. A multiple-mode resonator (MMR) is first constituted to equally allocate its first three resonant frequencies in the 3.1–10.6-GHz UWB band. Two capacitive-ended interdigital coupled lines are then formed to assign their transmission zero towards the fourth-order resonant frequency of this MMR, thereby suppressing the first spurious passband. Moreover, two outer arms in the interdigital lines are properly tapered to compensate the phase imbalance or group delay near the UWB upper-end relying on extra capacitive-ended stubs. And finally, two UWB filters with one- and two-MMRs are designed and implemented to experimentally demonstrate the improved out-of-band performances, i.e., widened/deepened upper-stopband and sharpened rejection skirts outside the UWB passband.     

一种基于正方环形谐振器的新型宽带带通滤波器

本文设计了一种紧凑型、宽通带、宽阻带的微带带通滤波器。该滤波器的设计是基于带有两个开路调节支节的正方谐振环。基于紧凑性的考虑,改变了传统方环谐振滤波器的馈电点和开路调节支节的位置,以便对谐振环进行折叠处理。这种改变并不影响谐振环的奇偶模特性。在输入和输出端口,通过两个叉指耦合结构对滤波器进行馈电,这种馈电方式增加了滤波器阻带的带宽和抑制度。滤波器的中心频率为4GHz,相对带宽为45％,通带内的回波损耗小于-12dB,群时延小于0．8ns,1-2．9GHz阻带抑制度大于12dB,5．3～7GHz阻带抑制度大于18dB。     

Compact Ultra-Wideband Microstrip/Coplanar Waveguide Bandpass Filter

A novel ultra wideband (UWB) bandpass filter is presented, using a compact coupled microstrip/coplanar waveguide (CPW) structure. The filter comprises of a single CPW quarter-wavelength resonator which is coupled to two microstrip open-circuited stubs on the other side of a common substrate. The two microstrip open-circuited stubs, which are about a quarter-wavelength long at the center frequency, can function as two resonators with associated coupling arrangement to the CPW. This forms a very compact three-pole filter. The proposed filter also exhibits a quasi-elliptic function response, with one finite-frequency transmission zero closer to each side of the passband. Thus, a high selectivity is achieved using a small number of resonators, which leads to low insertion loss and group delay across the passband. The performance is predicated using EM simulations and verified experimentally. The experimental filter shows a fractional bandwidth of 90% at a center frequency of 6.4GHz, with two observable transmission zeros (attenuation poles) at 1.95 and 10.36GHz, respectively. Furthermore, it has a very small size only amounting to 0.25 by 0.08 guided wavelength at the center frequency     

Ultra-Wideband (UWB) Bandpass Filter With Embedded Band Notch Structures

A compact ultra-wideband (UWB) bandpass filter (BPF) with narrow notched (rejection) band in the UWB passband realized on a microstrip line is implemented and presented in this letter for use in wireless communication applications within the unlicensed UWB range set by the Federal Communications Commission (FCC). The filter consists of five short-circuited stubs separated by nonredundant connecting lines in order to exhibit a high selectivity filtering characteristic. The narrow notched (rejection) band was introduced by using a new technique which involves embedding open stubs in the first and last connecting lines in order to reject any undesired existing radio signal which may interfere with the determined UWB passband. The bandwidth of the notched filter can be controlled by adjusting the width of the stubs or the gaps or both. The length of the stubs can be tuned to select a specific frequency for the notched band. The embedded stubs can be used to excite single or double band-reject response. Two UWB BPFs with narrow notched band having a fractional bandwidth (FBW) of about 4.6% and 6.5% were realized theoretically and verified by full-wave EM simulation and the experiment. Excellent agreement between the predicted and measured results was obtained and is demonstrated     

A Novel Wideband Bandpass Filter Using A Cross-Shaped Multiple-Mode Resonator

A novel wideband bandpass filter (BPF) using a cross-shaped microstrip multiple-mode resonator (MMR) is presented in the letter. The MMR is composed of a section of open-ended microstrip-line and a pair of short-ended stubs. Its three resonant modes are used to construct the passband of the proposed BPF. And two coplanar waveguides are used as the input/output transmission-lines to improve the coupling between the MMR and input/output transmission-lines. The filter has been investigated numerically and experimentally. Both simulated and measured results show that the filter has a good performance, including controllable bandwidth from 66% to 114%, low insertion loss (lower than 0.78 dB), and a small group delay variation.     

Implementation of Compact UWB Bandpass Filter With a Notch-Band

An ultra-wideband (UWB) bandpass filter on microstrip line with notch-band, compact-size and improved upper-stopband performances is presented and implemented. A modified non-uniform resonator is at first formed by transversely attaching three pairs of impedance-stepped stubs. Its resonance behavior is thoroughly characterized so as to allocate the first three resonant frequencies within 3.1-10.6 GHz band while suppressing spurious harmonics in the upper-band. As this resonator is linked at two sides with two feed lines via interdigital coupled lines with enhanced coupling degree, a preferred UWB passband is realized. Then, one of two arms in the coupled-line sections is largely extended and folded, aiming to create a notch band at the frequency of 5.6 GHz by virtue of out-of-phase transmission cancellation. Two filter prototypes are optimized and fabricated to demonstrate the notch-band-included and upper-stopband-improved UWB bandpass performances.     

五陷波超宽带天线的研究与设计

为滤除窄带信号对超宽带通信系统的干扰,研究并设计了一种具有五个陷波特性的超宽带天线。采用微带线馈电,在辐射贴片上刻蚀一个椭圆形开环谐振器,并在馈线旁制作了四个不同尺寸的U 形寄生短截线,以实现天线的陷波特性,天线尺寸为30 mm×40 mm×0.8 mm。仿真实验验证了天线工作频率范围为2.8~12 GHz;有效滤除了WiMAX 波段(2.94~3.42 GHz)、INSAT 波段(4.42~4.53 GHz)、WLAN 波段(5.32~5.5 GHz)、X 波段上行频(7.01~7.27 GHz)和X 波段下行频(7.57~8.05 GHz)。实测数据表明,天线的工作频段、方向性、增益及五个陷波特性等性能指标良好。     

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.     

Ultra-Wideband Compact Circularly Polarized Antenna

In this research work, a circularly polarized (CP) monopole antenna is designed for Ultra-Wideband (UWB) applications. The CP UWB antenna is be made up of a reformed ring patch and ground plane. The slots and stubs are inserted in the ground to achieve CP in the UWB antenna. This antenna attained an Axial Ratio Bandwidth (ARBW) of 5 GHz (4.0–9.0 GHz) that lies in the UWB frequency range that is from 3.1 to 10.6 GHz. The designed antenna has a radiation efficiency of around 80% for the complete UWB frequency range. The CP UWB antenna is designed and fabricated using the FR4 with a compact size of 32?×?30?×?1.6 mm³ and with a peak gain of 6.8 dBi. Tested results are in good resembles with simulated ones.

     

基于环形谐振器的平衡式带通滤波器

提出了一种基于多模环形谐振器实现的平衡式带通滤波器, 其主要由加载了电阻和短路枝节的环形谐振器和两对平衡端口构成.所提出的滤波器能够以单个谐振器获得差模的双模响应, 并且具有结构简单, 共模抑制高, 带宽可进行有限控制(4% ~ 9%)的优点.为验证理论预期的可实现性, 在RO4003C基板上设计了一个工作在1.87 GHz的平衡式带通滤波器.实验结果表明该滤波器的20-dB阻抗匹配带宽为8.9%, 中心频率处的插入损耗为0.86 dB, 在1 ~ 3 GHz频率范围内的共模抑制大于30 dB.     

X波段阶梯阻抗微带带通滤波器设计

设计了一款X波段的多模带通滤波器,并给出了仿真与实验结果。采用恒定阻抗枝节加载3个阶梯阻抗枝节的方式,构成滤波器的主体;利用表面电流分布图获得影响带内极点分布的枝节参数,通过调整阶梯阻抗枝节参数优化滤波性能。为实现更好的带外抑制能力,滤波器两端各串联一对平行耦合线,在14 GHz引入一个传输零点。实验测试结果显示,所设计滤波器的中心频率为9.76 GHz,带宽为2.4 GHz,30 dB/3 dB矩形系数为1.63,相对带宽为25%,带内插入损耗大部分小于1 dB,大部分回波损耗高于15 dB,与仿真结果较为吻合。