基于倒π型谐振器的双陷波微型超宽带滤波器设计

针对传统的超宽带滤波器设计尺寸偏大和陷波深度不足的问题,提出了一种基于倒π型谐振器的双陷波超宽带滤波器。通过在超宽带滤波器两端加载宽型开路枝节在通带内形成传输零点,并在滤波器上方耦合倒π型谐振器,实现通带内的双陷波特性。选用高介电常数的基板材料大幅度缩小滤波器的整体设计尺寸,实现微型化设计。测试结果表明,该滤波器通带范围为2.9～12.0 GHz,通带内插入损耗在1 dB以内,在5.76～6.14 GHz和7.82～8.45 GHz陷波深度分别达到了-20.6 dB和-31.6 dB。测试结果和仿真结果基本一致,说明该滤波器在通带内能够有效地避免无线局域网WLAN信号(5.725～5.850 GHz)和X波段卫星信号(7.900～8.395 GHz)的干扰,为平面型陷波超宽带滤波器的设计提供了新的思路。     

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。     

具有可控双陷波特性的超宽带滤波器设计

在多模谐振器的基础上,设计了一种新型的具有双陷波特性的超宽带滤波器。该滤波器在十字形谐振器的基础上加载了一对阶跃阻抗谐振器及两组短路反耦合线结构。设计得到的滤波器尺寸紧凑,且可实现滤波器谐振频率及陷波点的独立可控。测试可得滤波器的通频带为1.8~12.1 GHz,3 dB相对带宽为148%,通带内插入损耗小于1 dB,两个陷波点频率分别位于5.15 GHz和6.98 GHz。结果表明,该超宽带滤波器能有效地抑制WLAN频段和C波段卫星信号的干扰,与仿真结果吻合良好。     

一种新型超宽带带通滤波器的设计

针对超宽带(UWB)系统易受无线网络信号干扰及传统的超宽带带通滤波器阻带较窄,不能有效抑制谐波的问题,提出了一种新型的UWB带通滤波器,该滤波器由两级交指梳状耦合谐振器级联组成,通过增加耦合指的个数来实现陷波特性,然后在两个交指谐振器的中间添加一个槽线锥形谐振器,使该滤波器具有抑制高次谐波特性,达到拓宽高阻带的效果,同时由于槽线谐振器的加入,陷波频段的抑制电平进一步提高.实验结果证明,所设计的滤波器既能保证3.1～10.6 GHz频段内的插入损耗小于3 dB,陷波频段为5.7～5.8 GHz,陷波频段的抑制电平高达-43 dB,同时又能拓宽高频阻带.     

基于微带-槽线过渡的超宽带滤波器

基于电磁耦合微带-槽线过渡结构,设计了一个结构紧凑、具有陷波和超宽阻带的超宽带带通滤波器。通过嵌入1个终端短路的阶跃阻抗微带枝节和底层的槽线耦合产生1个可调节的陷波;同时,在上层微带输出端添加开路枝节和扇形结构获得超宽阻带的特性。该超宽带带通滤波器的中心频率为6.85 GHz,3dB通带为1.95~13.15GHz,相对带宽达到148%。与以往的超宽带带通滤波器相比,其具有结构简单、尺寸小和带外抑制良好等特点,仿真和测试结构吻合较好。     

一种SLR结构陷波宽带滤波器的设计

在枝节加载谐振器（Stub-loaded Resonator,SLR）的理论基础上设计了一种陷波宽带滤波器,应用于3.0~6.7 GHz频段。该滤波器由一个倒T形短路枝节加载谐振器（Short SLR,SSLR）和一个基于半波长SIR基本结构的阶跃阻抗枝节加载谐振器（Stepped Impedance SLR,SISLR）构成。与传统陷波滤波器相比,该滤波器没有采用传统的缺陷地结构或缺陷微带结构,其陷波特性由SISLR与SSLR耦合所致,能够实现更好的设计灵活性。对电路进行了仿真和实物制作,仿真结果表明,插入损耗和回波损耗分别优于0.3 dB和12.2 dB,陷波的中心频率位于5.8 GHz,其分数带宽为6.8%。测试结果与仿真结果基本一致,体现了良好的电路性能。     

基于T型枝节加载SIR的双频微带滤波器的设计

针对当前通信系统需要滤波器支持多频段、小型化和高性能等要求,提出了一种基于T型枝节加载SIR的频率独立可控双频微带滤波器结构。针对该谐振器,利用提出的特殊电耦合结构实现滤波器的小型化,并引入零度馈电结构构造传输零点来改善阻带抑制,最终得到覆盖WLAN 2.4 GHz和WLAN 5.2 GHz两个频段且占用尺寸仅为16.5 mm×21.7 mm的双频微带带通滤波器。由仿真结果显示,两个通带的中心频率分别为2.45 GHz和5.2 GHz,带内最小插入损耗分别为0.35 dB和0.47 dB,带内最小回波损耗分别为-44 dB和-34.8 dB,3 dB相对带宽分别为28.9%和11.3%,阻带抑制也因引入三个传输零点而大大改善。该滤波器结构整体尺寸小、插损低、频带宽且带外抑制特性好,具有一定的实际应用价值。     

一种紧凑型二端口双陷波超宽带MIMO天线

提出了一种紧凑型的二端口双陷波超宽带MIMO 天线。该天线由两个圆形单极子和一个缺陷地结构组成,在两个单极子辐射片上刻蚀开口圆环槽,并在两个50Ω馈电微带线旁分别增加终端短路的低-高-低阶跃阻抗谐振器,实现了双陷波的功能,分别抑制了无线局域网WLAN(5.15～5.85 GHz)和802.16无线城域网WiMAX(3.4～3.8GHz)信号对该天线系统的干扰;并在介质板地层和顶层增加隔离枝节,提高了隔离度。实验结果表明:该天线在-10dB 的工作带宽为3.0～13.8 GHz,第一个陷波带宽为3.37～3.85GHz,第二个陷波带宽为5. 02～6.14 GHz,有效抑制了WiMAX 和WLAN信号干扰;工作频带内,最小隔离度为13.5 dB,最大增益为4.94 dB,最大辐射效率为96.6%,包络相关系数小于0.07。测试表明该天线适用于多输入-多输出超宽带(MIMO-UWB)系统,且该天线结构紧凑,尺寸仅为47.5 mm×47.5 mm×0.8 mm,易用于便携式设备。     

三陷波微带超宽带滤波器设计

旨在解决超宽带滤波器存在的尺寸偏大、陷波个数不足的问题,采用改进的多模谐振器以及新型缺陷接地结构,提出了一种具有三陷波和较好选择性的微带超宽带滤波器.设计谐振器在阶梯阻抗谐振器两侧和下方加载枝节,构建了超宽带滤波器的通带和两个陷波,并设计缺陷地面结构,在增加陷波的同时对陷波特性加以改善.经仿真显示,该滤波器通带带宽为2...     

基于加载非对称开路枝节谐振器的带通滤波器

基于新型的加载非对称开路枝节的阶梯阻抗谐振器,设计了一种具有高频率选择性的单频微带滤波器.该滤波器采用非对称的开路枝节作为容性负载,抑制高次杂散频率,具有较宽的上阻带,中心频率(2.4 GHz)处的插入损耗为0.6 dB.与传统结构相比,该滤波器在相同的谐振频率下尺寸减小了45％.调整新型阶梯阻抗谐振器的尺寸,还能实现中心频率为3.5 GHz单频和2.4 GHz/3.5 GHz双频带通滤波器.     

Design of an Ultra‐Wideband Antenna Using a Ring Resonator with a Notch Function

This paper describes an ultra‐wideband (UWB) antenna that uses a ring resonator concept. The proposed antenna can operate in the entire UWB, and the IEEE 802.11a frequency band can be rejected by inserting a notch stub into the ring resonator. The experiment results indicate that the measured impedance bandwidth of the proposed antenna is 17.5 GHz (2.5 GHz to at least 20 GHz). The proposed UWB antenna has omnidirectional radiation patterns with a gain variation of 3 dBi (1 dBi to 4 dBi).     

Microstrip Lowpass Filter with Very Sharp Transition Band and Wide Stopband

A novel lowpass filter with a very sharp transition band and wide stopband is proposed. The proposed filter is based on T‐shaped patches which are etched in symmetrical structures and folded open stub. To obtain a wide stopband, we have used stub loaded semi‐circle stepped‐impedance structures. By designing the resonator with high inductance and capacitance, a very sharp transition band is achieved. The proposed filter has a 3‐dB cutoff frequency at 2.37 GHz and a 40‐dB rejection at 2.44 GHz. The stopband with an attenuation level better than –13.2 dB is up from 2.4 GHz to 16 GHz, and consequently we have reached the high and wide rejection in stopband with compact size. Good agreements between the simulated and the measured results are presented.     

基于枝节加载谐振器的新型三频带通滤波器设计

提出了一种新型平面三频带通滤波器,该滤波器由一个加载短路枝节的阶梯阻抗谐振器,一对加载开路枝节的背靠背E型谐振器,以及包含源负载直接耦合的馈电结构组成.所采用的枝节加载谐振器的多模工作特性使滤波器的体积大大减小,同时每个通带的位置及其耦合特性都能够独立调谐.另外,通过源负载直接耦合引入通带两侧的传输零点,实现了滤波器良好的频率选择性.最后设计并加工了一款高选择性小型化三频带通滤波器,其三个通带的中心频率分别为2.0GHz,3.95GHz和6.35GHz,插入损耗均小于2.5dB,带内回波损耗均优于14dB,实验结果与仿真结果吻合良好.     

An Ultra-Wideband Bandpass Filter With an Embedded Open-Circuited Stub Structure to Improve In-Band Performance

In this letter, we present a compact ultra-wideband bandpass filter (BPF) with a notch band in the BPF performance by using an embedded open-circuited stub structure. The filter mainly consists of conventional stepped impedance resonator (SIR) as the multiple-mode resonator and two enhanced coupled input/output lines. The bandwidth can be analyzed by using the image-parameter method to obtain the proper dimension of the coupled lines and verified by using electromagnetic (EM) simulation. The embedded open-circuited stub structure in the SIR is used to produce a narrow notched band at 5.8 GHz, which its frequency position and bandwidth can be tuned by its physical parameters. The measured 3 dB fractional bandwidth of 113.8% and narrow notched band with 25 dB rejection is achieved. Good agreement between the EM simulation and measurement is obtained.      

Compact Dual Band Bandpass Filter Using Novel E-Type Resonators With Controllable Bandwidths

A compact microstrip dual band bandpass filter (BPF) using novel E-type resonators is presented in this letter. The E-type resonator is a short-circuited stub loaded hairpin resonator, two passband frequencies of which can be regulated by adjusting the characteristic impedance and electrical length of the hairpin and the stub. By combining pseudo-interdigital coupling structure, the coupling coefficients of two bands can be adjusted to a desired value in a relatively wide range. In addition, hook feed line is introduced to obtain desired external coupling degrees for two bands. Thus, controllable fractional bandwidths (FBWs) can be achieved. Two two-order 2.45/5.25 GHz dual band BPFs with 3 dB FBW 7%/7% and 5%/5%, respectively, are designed. The measured result agrees well with the simulation.      

Small Ultra-Wideband (UWB) Bandpass Filter With Notched Band

A compact ultra-wideband (UWB) bandpass filter (BPF) with notched band has been proposed and implemented in this letter. H-shaped slot is studied and adopted to tighten the coupling of inter-digital capacitor in order to improve the BPF's performance. Three pairs of tapered defected ground structures (DGS) are formed to assign their transmission zeros towards the out of band signal, thereby suppressing the spurious passband. Combining these two structures we obtain a small sized UWB BPF. Meander line slot is developed to reject the undesired wireless local-area network (WLAN) radio signals. An experimental UWB filter with notched band was fabricated with 35% less length as compared to an embedded open-circuited stub. The measured BPF insertion loss is less than 1.0 dB throughout the pass band of 2.8 to 10.8 GHz, the variation of group delay less than 0.20 ns in this band except for the notched band, and a wide stopband bandwidth with 20 dB attenuation up to at least 20.0 GHz.     

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.