宽阻带小型化双频带通滤波器

文中提出了一种具有宽阻带的紧凑型双频带通滤波器,它采用了折叠短路枝节负载谐振器、紧凑型微 带单元谐振器(CMRC)和阶跃阻抗谐振器结构。由于多个谐振器产生了五个可控传输零点(TZ),该滤波器实现了两个 通带之间的良好隔离度以及宽阻带特性。制作并测试了尺寸紧凑的双频带通滤波器实验样品,测试结果显示,第一通 带和第二通带的中心频率/ 插入损耗分别为0. 66 GHz/0. 8 dB 和1. 73 GHz/0. 7 dB,阻带频率高达10. 5 GHz,抑制水平 超过15 dB。     

基于开路T型结构的小型化超宽阻带滤波器设计

传统滤波器由于寄生通带的存在,其高频阻带性能较差。随着超宽带雷达系统和超宽带通信系统的发展,小型化宽阻带的滤波器已成为一项紧迫的技术课题。该文论述了一种普适性的基于开路T型结构的小型化超宽阻带滤波器结构,这种滤波器和传统滤波器相比,结构极为紧凑,5倍基频范围内的寄生通带均被抑制,而通带性能保持良好。基于此结构实际制作了一个截止频率为2.9 GHz的低通滤波器,测量得到的通带内平均插入损耗仅0.67 dB,带内平均驻波比为1.33,过渡带陡峭,40 dB矩形系数仅1.096,而所测得的阻带从3.23 GHz到10.30 GHz之内谐波抑制大于36 dB,从10.30 GHz到15 GHz之内谐波抑制大于27 dB;该滤波器的长度仅为传统的同类型滤波器的长度的37.1%,面积大大减小。仿真和测量结果表明该类型滤波器同时满足了小型化和宽阻带的性能需求。     

Parallel-coupled line filters with enhanced stopband performances

A new class of parallel-coupled line filters with broad stopband response is introduced. The design is based on the synthesis of bandpass prototypes with pre-defined upper stopband characteristics. The new filters have uniform- and stepped-impedance resonators, some of which are loaded by open-circuited stubs at their open-circuited ends. A seventh-order filter implementation is presented with a fundamental passband centered at 1 GHz. The measured wide-band transmission characteristic of the filter demonstrated a broad upper stopband and was in agreement with simulations. The performance of the new filter is also compared with the characteristic of a conventionally designed filter to highlight the advantages of the proposed design method.     

一种超宽阻带微带低通滤波器的设计

基于传统阶跃阻抗滤波器,提出了一种易于实现的超宽阻带微带低通滤波器改进设计方案。低阻抗线部分采用扇形微带结构,在同等阶数下,该结构的滤波器与传统阶跃阻抗滤波器相比,具有更紧凑的电路结构以及更好的阻带特性。在滤波器末端并联开路短截线,使得阻带增加额外传输陷波点来抑制寄生通带。利用ADS和HFSS仿真软件对滤波器结构进行优化设计,并进行了实物的加工和测试。实测结果表明,通带3 dB 截止频率为2 GHz,通带内0-1.8 GHz 回波损耗大于20 dB,3-20 GHz 频率范围内的阻带抑制能达到25 dB 以上。     

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.     

Microstrip Coupled-Line Lowpass Filter with Wide Stopband for RF/Wireless Systems

We present the design of a compact microstrip lowpass filter with a wide stopband which is up to ten times the cutoff frequency. The filter is based on a coupled-line configuration and shunt open stubs. The open stubs create additional transmission zeros, which are used to extend the stopband of the filter without any additional components or cascaded units. A prototype lowpass filter with a 3 dB cutoff frequency of 0.428 GHz and a 15 dB stopband extended up to 4.77 GHz is fabricated to validate the theoretical predictions.     

Wide-stopband microstrip low-pass filter using modified semi-circle patch resonator

In this article, a compact microstrip low-pass filter with elliptic-function response is proposed. To achieve wide stopband, modified semi-circle patch resonator in series with semi-circle stepped impedance resonator is used. The proposed structure achieves a wide stopband and a high selectivity within a small circuit area. The proposed filter has 3-dB cutoff frequency at 1.71?GHz and 20?dB rejection at 2.1?GHz. The stopband with the attenuation level better than ?18.7?dB is from 2.08 up to 16?GHz, and consequently we have reached the high and wide rejection in stopband as well as compact size. The structure is simulated, fabricated and measured. The measured results are in good agreement with the simulated results.     

Compact wide stopband lowpass filter using spiral loaded tapered compact microstrip resonator cell

A new spiral loaded tapered compact microstrip resonator cell (SPLT-CMRC) is presented. The addition of spiral stubs to the CMRC creates transmission zeroes in the stopband which extended the stopband of the ?lter. The proposed resonator is used to design a compact lowpass ?lter (LPF) with wide and high rejection in stopband. The fabricated ?lter has a 3 dB cutoff frequency at 8 GHz. The insertion loss in the passband is less than 0.2 dB from DC to 7.2 GHz. The proposed ?lter has wide stopband from 9.47 to 40 GHz with attenuation level of ?20 dB. The demonstrated filter is designed and fabricated. There is a good agreement between the measured and simulated S-parameters.     

Dual‐Transmission‐Line Microstrip Equiripple Lowpass Filter with Sharp Roll‐Off

A novel application of a dual‐transmission line is proposed to design a lowpass filter (LPF). The proposed structure uses only transmission line elements to produce an equiripple LPF response with sharp roll‐off. Design equations are derived using a lossless transmission line model. Controlling the electrical lengths, three transmission‐zeros are realized in the stopband to obtain a sharp roll‐off rate and wide stopband bandwidth. A single unit microstrip LPF with a 3‐dB cut‐off frequency at 1.0 GHz having a roll‐off of 135 dB/GHz along with a stopband bandwidth of 69.5% is designed for validation.     

A novel microstrip lowpass filter with sharp roll-off and ultra-wide stopband using SICMRC

This paper presents a novel microstrip lowpass filter with sharp roll-off and ultra-wide stopband using stepped-impedance resonator and bended transmission line structure. The filter includes stepped-impedance prototype filter and stepped-impedance compact microstrip resonator cells that are combined in one structure. The proposed filter has good specifications such as sharp roll-off, ultra-wide stopband and low insertion loss. The transition band is approximately 0.25 GHz from 1.75 to 2 GHz with corresponding attenuation levels of ?3 and ?40 dB. The attenuation level in the stopband is better than ?20 dB that is achieved from 1.94 to 23 GHz, and the insertion loss in the passband is less than 0.4 dB. The proposed filter is fabricated and measured, and the simulation and measurement results are found to be in good agreement with each other.     

Compact Ultra-Wideband Bandpass Filter With Improved Upper Stopband

In this letter, a design of a compact bandpass filter with wide upper stopband is presented for the ultra-wideband communication systems. The filter structure is composed of a modified square slot-line resonator with parallel microstrip feed lines. Improved upper stopband is obtained by exploiting the frequency dispersive coupling behavior between the feed lines and the resonator. Measurements show that the 20.9 dB upper stopband extends at least up to 20 GHz. Filter occupying area is 0.26lambdag times 0.28g, lambdag being the microstrip line guided wavelength at 6.85 GHz.     

Design of compact, broad-stopband lowpass filter using modified stepped impedance hairpin resonators

A compact elliptic function lowpass filter using a stepped impedance hairpin resonator is proposed. The filter has the advantages of compact size, low insertion loss, easy fabrication, a wide stopband, and sharp cutoff frequency response. In order to cause a sharp cutoff frequency response and the wide stopband suppression, a coupled stepped impedance resonator is taken into consideration for the newly proposed lowpass filter. A demonstration filter has been designed, fabricated and tested, and the results agree well with the theory. The size of the filter is less than 0.037 lambdag times 0.093 lambdag, where lambdag is the waveguide length at the cutoff frequency 1.5 GHz, and the 10 dB rejection stopband can be extended to more than 15 GHz. The filter is useful for many microwave system applications.     

小型高带外抑制超宽带滤波器设计

为了提高滤波器的带外噪声抑制,并兼顾小型化,提出了一种新型超宽带滤波器设计。首先,利用分路电磁耦合结构在通带两侧实现了2个传输零点,通过调节中间金属片与螺旋缺陷地可实现对2个零点的单独调节,由此实现了高带外抑制,且有利于滤波器的小型化;然后,利用基片集成波导与周期性缺陷地结构,在进一步提高频率选择性的同时,实现了较好的阻带性能;最后,设计并加工了一款工作频率为8.1 GHz、带宽为67%的滤波器。结果表明,仿真与测试结果吻合良好,证明了该设计方法的可靠性。     

一种S波段小型宽带微带带通滤波器优化设计

基于并联短截线谐振器与联接线变换器构成的传统微带带通滤波结构,提出了一种工作在S波段的改进型宽带带通滤波器。以三阶结构为例,通过将两侧并联短截线进行弯折,形成耦合线结构;将中间并联短截线进行拆分,变为并联的短路线和开路线,实现了在通带性能基本不变的前提下,获得阻带可调控的传输零点,进而提高过渡带陡峭度。为了进一步抑制阻带,在滤波器两侧级联扇形微带低通滤波结构,改善阻带性能。利用ADS和HFSS仿真软件对滤波器结构进行仿真优化设计,并最终进行了实物加工和测试。实测结果表明,通带内2~4 GHz插入损耗小于0.7 dB,回波损耗大于17 dB,通带外4.6~6.5 GHz 阻带抑制达到20 dB 以上。     

Uniplanar compact wideband bandstop filter

A uniplanar wideband bandstop filter is proposed using two bent open-end stubs. The proposed filter consists of the bent connecting line of /spl lambda//sub g//2 between two bent /spl lambda//sub g//4 stubs, which results in wideband design with a rejection bandwidth of 90% at 2.05 GHz. Further, the connecting line and stubs have the same characteristic impedance. The proposed filter compared to the conventional one is also more compact. The area of the novel filter is (/spl lambda//sub g//4)/sup 2/ at the center frequency of the stopband, while the area of the filter realized using the nonbent stubs and connecting line is 2(/spl lambda//sub g//4)/sup 2/ for the same stopband characteristics.     

一种高滚降宽阻带低通微带滤波器

普通的阶梯阻抗低通滤波器滚降系数一般低于80 dB/GHz,阻带抑制小于20 dB,使其应用受到较大限制;文中首先从理论上分析并设计了具有宽阻带优势的阶梯阻抗滤波器,然后引入扇形短截线结构提高滚降系数,设计了一款通带为0~6 GHz 的高滚降宽阻带的微带低通滤波器。利用ADS 和HFSS分别对滤波器进行了建模、仿真和优化;最后采用RO4003 板材加工并对实物进行了测试。测试结果显示,所设计的滤波器3 dB 截止频率为6.02 GHz,滚降系数为123 dB/ GHz,阻带6.24~20 GHz,阻带抑制大于30 dB。     

A novel cross-shape DGS applied to design ultra-wide stopband low-pass filters

This letter presents a novel low-pass filter with an ultra-wide stopband. The proposed filter is comprised of a new cross-shape defected ground structure (CSDGS). By using this structure, the filter not only supports conventional DGS performances with a sharp rejection, but also exhibits an ultra-wide stopband. For the deigned low-pass filter, an insertion loss of less than 2dB from dc to 3.5GHz and the rejection is better than 20dB from 4.3 to 15.8GHz. Predicted performances show widened and deepened stopband beyond the low passband. Furthermore, it is confirmed by measurement.     

Metallic E-plane filter with cavities of different cutoff frequency

A planar integrated circuit filter with multiple all-metal inserts and multiple abrupt waveguide step-wall discontinuities is introduced which achieves broadband high attenuation in the second stopband. The design is based on field expansion into suitably normalised eigenmodes which yield directly the modal S-matrix. This theory allows the immediate inclusion of both the higher-order mode interaction at all discontinuities and the finite thickness of the inserts. Computer-optimised design data for a five-resonator Ka-band prototype filter at 27 GHz midband frequency provide a minimum stopband attenuation of 50 dB between 27.5 and 44.5 GHz.     

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.     

具有良好选择性及带外抑制的小型低通滤波器

本文提出了一种具有良好选择性以及宽带带外抑制的小型低通滤波器结构。滤波器的每一级由一段微带线和交指电容构成。基于对每一级结构的分析,我们可以确定通带的范围。为了进一步提高带外的抑制性,对单级滤波器进行了周期性的级联。通过产生多个带外衰减极点来实现带外的宽带抑制。此滤波器3dB 截止频率3.67GHz,带内插损-0.9dB,带内回波损耗低于-13dB。通带到阻带的选择度为160dB/GHz。带外抑制从3.8GHz 到13.1GHz 低于-20dB。