采用双开口方谐振环对的紧凑微带双频带通滤波器

提出了一种零度馈电、具有开口谐振环对的紧凑微带双频带通滤波器,适用于短距离无线通信2.4GHz频段和3.5GHz固定无线接入(FWA)的频段。此滤波器使用开口谐振环作为基本谐振器单元,通过电耦合实现了第一带通特性,通过调谐内外环的间距产生第二通带。为了提高带外衰减,通过设计零度馈电结构来引入四个传输零点,从而获得了高选择性特性,该滤波器设计简单、结构紧凑。最后,仿真设计和制作了滤波器样品,仿真与实测吻合较好,满足了设计要求。     

具有四陷波特性的小型化超宽带滤波器

为了解决传统具有陷波特性的超宽带滤波器陷波深度不足和陷波较少的问题，提出了一种小型化四陷波超宽带滤波器。通过采用非对称耦合技术、在两端馈线处嵌入开路枝节以及在超宽带滤波器上加载新型双开环谐振器、C型谐振器的方式，实现通带内的四陷波特性。该超宽带(Ultra-Wideband, UWB)滤波器通带为2.77～11.1GHz，相对带宽为120%，在3.54 GHz、5.62 GHz、6.84 GHz和8.24 GHz处产生四个陷波，能够避免全球微波互联接入(WiMAX)、无线局域网(WLAN)、印度国家卫星通信C频段和X卫星通信上行频段对超宽带系统的干扰，适用于超宽带无线通信系统。最后，对设计制作的实物进行测试，测试结果与仿真结果基本一致。     

基于微带三模谐振器的超宽带带通滤波器设计

提出一种基于微带三模谐振器的超宽带带通滤波器设计.该滤波器由一个中心加载阶跃阻抗开路枝节的三模谐振器,及两组用于抑制谐波的新型哑铃型缺陷地结构组成.使用交指型馈电方式及在馈电处的地板开槽实现超宽带需要的的强耦合,利用缺陷地结构抑制高次谐波实现良好的阻带特性.仿真结果表明,所设计的滤波器通带3 dB相对带宽达到80％(4.06～9.48 GHz),通带内插入损耗小于0.58 dB,回波损耗大24 dB,通带外10 dB阻带覆盖到30 GHz,通带两侧附近均有一个传输零点,获得了陡峭的通带边缘,较好地实现了美国联邦通信委员会(FCC)授权的超宽带通信系统的频谱使用要求.该滤波器结构简单,谐振器自身尺寸小于中心频率下0.5λg×0.5λg.最小带线和最小缝隙宽度均不小于0.1 mm,易于低成本加工,具有较高的实用价值.     

具有宽上阻带和双陷波的超宽带滤波器

基于偏置环形谐振器和加载电容器的缺陷地结构设计了一种具有宽上阻带和双陷波的超宽带滤波器。利用奇偶模分析法分析三阶接地短截线的传输极点与结构的对应关系，得到了一个具有五个传输极点的结构。通过采用三阶接地短截线结构和偏置环形谐振器的级联结构得到通带和宽上阻带，通带范围为2.95～12.24 GHz，相对带宽达到122%，上阻带大于10 dB，衰减范围至28.04 GHz。引入两个相同的H形缺陷地结构，并且在缝隙处焊接电容器，在2.69 GHz处共同产生传输零点来改善滤波器带外抑制特性。使用两个不同尺寸的半H形缺陷地结构分别在5.64 GHz和8.31 GHz处产生陷波，陷波衰减分别为16 dB和20 dB，提高滤波器的抗干扰能力。     

一种双频段方向图可重构的方形天线的设计

提出了一种新型的双频段方向图可重构方形天线。该天线由贴片-槽-方形环及四个带 U 型槽的类喇叭形寄生单元构成。通过改变 U 型槽结构的深度,天线可分别工作在2.45 GH 和5.25 GHz 两个频点。通过控制贴片-方形环-喇叭形寄生单元之间通断,选择相应的寄生单元,天线可分别在θ=45°和θ=90°平面上实现4个方向的定向辐射。该天线在2.42~2.52 GHz 和5.21~5.32 GHz 两个频段上具有较好的定向性,适用于抗干扰性能要求较高的多频点工作的无线通信系统。     

基于Si-BCB工艺Ka波段双模带通滤波器

介绍了一种应用于毫米波晶圆级集成基于Si BCB工艺的Ka波段双模带通滤波器。微带线结构的全波长谐振器具有低辐射特性,全波长环形阶跃阻抗谐振器（step impedance resonator, SIR）有两种正交谐振模式,可以减小滤波器尺寸。通过对基于环形谐振器的双模滤波器进行奇偶模分析,确定谐振器的设计参数。采用宽边耦合结构设计输入输出端口,具有高耦合度。仿真结果表明中心频率35 GHz,通带内插损1.2 dB,回波损耗优于30 dB,BW3 dB为15%。最后,采用Si BCB工艺制作滤波器并完成测试。测试结果为中心频率33.3 GHz,通带内插损1.17 dB,回波损耗优于30 dB,BW3 dB为18%。测试结果与仿真结果基本吻合。     

采用阶梯 T 型谐振器的双陷波 UWB 滤波器

为有效抑制印度国家卫星通信C频段和X卫星频段对超宽带通信系统的干扰,提出了一种新型双陷波超宽带滤波器。该滤波器采用阶梯T型多模谐振器(multimode resonator, MMR)与缺陷地结构(defected ground structure, DGS)的交趾耦合,实现超宽带特性。采用非对称耦合线及在MMR两侧耦合分裂环谐振器的方法,分别在6.67～7.06 GHz, 7.47～7.57 GHz两个频段内产生陷波。实测结果与仿真结果吻合较好,该滤波器的通带范围为3.03～11.50 GHz, 3 dB带宽达到123%,插入损耗仅有0.87 dB,两处陷波中心频率分别在6.87 GHz和7.52 GHz,陷波深度均大于20 dB,且整体尺寸紧凑,仅有16 mm×8 mm大小。     

用于复杂电磁环境的能量收集表面

用于在多频带、极化方式多样、宽入射角度的复杂电磁环境中有效收集电磁能量,提出了一个超材料单元,它由8个开口谐振环并按照正八边形排列,内部添加一个正八边形的寄生贴片.8个相同的开口谐振环经旋转排列,结合内部的寄生贴片形成中心对称结构,设计了一种新颖的电磁能量收集表面,具有多频、宽入射角度、极化不敏感的工作特性.使用微波仿真软件CST对组成该电磁能量收集表面的超材料单元的结构尺寸进行了分析和优化,对垂直入射的电磁波的电磁能量收集效率、单元上的能量分布以及S参数进行了研究.仿真结果表明,当电磁波垂直入射时,在5.75、6.5、6.84、7.56、7.98、8.55 GHz 6个频点处分别达到82％、79％、61％、71％、70％、73％的最大收集效率;在0°～60°以20°为间隔的斜入射下,该表面对TE波和TM波都可以保持有效的收集效率.     

基于中心对称结构的带宽可重构滤波器设计

为适应需求日益复杂的无线通信环境，充分利用紧缺的频谱资源，设计实现了基于中心对称结构及变容二极管的电可调微带带通滤波器。通过电磁仿真软件HFSS进行仿真实验，在加载枝节的开口环谐振器结构上，引入叉指结构和马刺线型耦合馈线完成滤波器的原型设计。在原有的基础上加入可调节电容值的变容二极管，调节低频传输零点，实现通带带宽可重构，从而达到灵活控制滤波性能的目的。实际测试表明该滤波器的初始相对带宽为5.1%,初始绝对带宽为170 MHz,变容二极管调节绝对带宽在140～200 MHz范围内，即82.4%～117.6%,中心频率在2.70～2.76 GHz,传输零点调谐范围在2.57～2.63 GHz,通带内插入损耗在0.9～1.5 dB,回波损耗在10～35 dB,测试结果与仿真基本相符，在S波段的带宽精密控制方向具有一定应用前景。     

0.5～2GHz宽带磁调谐带阻滤波器原理与设计

用单晶铁氧体谐振器替代普通微波滤波器的分布参数谐振器构成滤波器。介绍了单晶铁氧体谐振器工作原理,给出了单晶小球的谐振等效电路及其Q值计算式,利用其铁磁共振原理,实现滤波器的多倍频程宽频带磁调谐。用传统滤波器设计方法,基于磁耦合带阻滤波器的工作原理并通过两次滤波器电路的简化,设计出单晶铁氧体带阻滤波器通带,给出了电路的仿真曲线。利用低通滤波器电感环球耦合,成功实现带阻滤波器的磁耦合结构,用单晶铁氧体带通滤波器设计方法设计带阻滤波器阻带调谐结构并给出了环球的结构参数。最后给出了滤波器的实测曲线,在0.5～2GHz通带内插损<2dB,电压驻波比小于2,阻带最小40dB带宽>8MHz,最大3dB带宽<150MHz,阻带深度>60dB。     

基于方形开环的双模滤波器设计

在传统方形开环谐振器的基础上,设计了一种新型的双模微带滤波器,该滤波器包含两个方形开环谐振器,在每个传统谐振器内部添加微带支路结构,通过微扰来实现频响特性的改善,由仿真结果可以看出,该设计的带内特性良好,带内波纹小于0.3dB,通带边沿均插入了传输零点,且传输零点处的S21〈40dB,截止边沿陡峭,实现了6%的相对带宽,整个滤波器的尺寸大小约为30mm×20mm,改进后的结构与传统结构相比降低了0.5GHz的中心频率,相对减小了16%的面积,进一步实现了小型化。     

A reconfigurable high ultimate rejection inductorless band‐pass filter by the use of N‐path passive mixers

In this paper, a band‐pass filter with a tunable bandwidth and the center frequency is introduced, which employs N‐path and N × M‐path passive mixer structures, for multiband multistandard wireless receivers. The center frequency of the proposed filter is tunable from 0.1 to 1 GHz, while its bandwidth is also adjustable from 6% to 34% of the center frequency at 100 MHz. The passband ripple is reduced by applying a Miller compensation technique, resulting in a worst‐case ripple of only 1.6 dB over the entire tuning range. An additional eight‐path filter is also utilized at the input of the circuit, which highly improves the out‐of‐band rejection of the filter as well as its out‐of‐band linearity. The noise figure and the input return loss are, respectively, better than 5 and 10 dB, and depending on the desired center frequency, the total power consumption of the proposed filter varies from 41 to 70 mW.     

Modeling and validation of high selective harmonic reduced bandpass filter using coupled resonators and defected ground structures

Recent developments in wireless communication systems demand good Band pass filter (BPF) with high quality factor and good selectivity to select the required signal from the adjacent signals. In this paper one coupled Band pass filter with centre frequency 2?GHz and 30?% Fractional Bandwidth (FBW) has been designed with rectangular split ring coupled resonators formed with conventional Microstrip transmission line. This designed BPF has been simulated with the help of MoM based IE3D electromagnetic EM simulation software. Here it is found that the proposed BPF provides second harmonic nearer to the twice of its passband centre frequency and some other few harmonics. Therefore, in this paper attention also has been given towards the suppression of harmonics with the help of Defected Ground Structures (DGS) in addition with the proposed coupled microstrip BPF. The proposed structure has been measured with Agilent vector network analyzer. There is a good agreement between simulated and measured responses.     

Digitally tunable ring laser using ladder filter and ring resonator

We propose a digitally tunable ring laser incorporating a ladder filter and a ring resonator. The widely tunable ladder filter consists of two input-output waveguides and a waveguide array, and it selects one channel from the periodic outputs of the ring resonator. With this device, the passband of the ladder filter is important in terms of obtaining stable lasing operation and it becomes narrower with increasing diffraction order. However, the free-spectral range of the filter is reduced with increasing diffraction order and this induces lasing mode instability. We therefore optimize the diffraction order of the ladder filter. The device is monolithically integrated by using the InP-InGaAsP material system. We achieved 37 channel 1000-GHz spacing digitally tunable laser operation. A promising way of improving the device performance is to use a chirped ladder filter because this filter has one dominant passband.     

新型双频窄带带通滤波器的设计

提出了1种新型双频窄带带通滤波器,由1段1/4波长的均匀阻抗线以及1/2波长的U型阶跃阻抗谐振器组成,输入输出采用抽头式.所设计滤波器中心频率为2.4/5.6 GHz,为无线通信系统中的常用频率.该滤波器的带外有3个传输零点的引入,增强了通带隔离度以及阻带的抑制特性,带内回波损耗低于-0.3 dB.双频窄带带通滤波器的...     

Selective linear phase filters possessing a pair of J-axis transmission zeros

A design technique is developed for prototype selective linear phase filters which have an equiripple passband amplitude response and a pair of j-axis transmission zeros in the stopband while maintaining a linear phase characteristic in the passband. Since the basic technique requires numerical optimization techniques, the element values for several cases have been tabulated together with detailed response characteristics. One important result is that for certain characteristics, one internal cross-coupling element may be designed to be zero. As a result, in the sixth degree case with only one extra cross-coupling element between elements 1 and 6 a significant improvement in both the amplitude and group delay performance can be achieved as compared to the Chebyshev case. Owing to its importance, this case is investigated in detail and a 2.6 GHz post decoupled combline filter has been constructed based upon this prototype.     

新型吸收式微带线带通滤波器的仿真设计

基于传统的梳妆线谐振式滤波器设计原理及微带线定向耦合器理论,提出了一种新型的吸收式带通滤波器,其特点是滤波器的电压驻波比不仅在通带内很好,通带外很大频率范围内驻波也小于3.5,这也是该滤波器与常用的反射式滤波器的区别。首先,该滤波器采用微带线结构实现,与传统LC结构滤波器相比,可应用于更高的频段;其次,该滤波器具有较宽的带宽;再者,该滤波器设计灵活简单、成本低、易于集成。通过MWO软件仿真优化,实现了通带中心频率为3500MHz、3d B带宽为479MHz、通带内插入损耗小于3d B、通带内电压驻波比小于2、带外驻波比在很大频率范围内小于3.5的新型微带吸收式带通滤波器的设计。     

Wavelength-swept fiber laser with frequency shifted feedback andresonantly swept intra-cavity acoustooptic tunable filter

This paper concerns a wavelength-swept fiber laser (WSFL) incorporating frequency shifted feedback and an intracavity passband filter, in which the wavelength of the modeless output is linearly, continuously and repeatedly tuned (in time) over a given range by modulation of the filter peak wavelength and filter strength. We show both numerically and experimentally that amplifier noise plays a key role in determining the operation of frequency-shifted fiber laser systems and that a “noisy” amplifier can be used to suppress the natural tendency of such lasers to pulse, allowing for continuous wave, modeless operation. Furthermore, we show that significant narrowing of a WSFL instantaneous swept linewidth can be obtained if the filter peak transmission wavelength is resonantly swept so as to follow the wavelength shift per pass due to the acoustooptic frequency shift. Using these ideas we go on to demonstrate and characterize a high-power diode-driven Er³⁺/Yb³⁺ WSFL incorporating a bulk-optic acoustooptic tunable filter (AOTF). Linewidths as narrow as 9 GHz, sweep ranges up to 38 nm and output powers as high as 100 mW are obtained. Furthermore, we demonstrate the generation of user definable average spectral output by synchronous modulation of the filter strength and multiwavelength pulsed output at higher sweep rates. Excellent agreement between the experimental results and those of the numerical modeling is obtained. Our simulations show that reduced linewidth (<0.02 nm) and improved scan linearity should be readily achievable with realistic system improvements. We believe such sources to be of considerable physical and practical interest, with applications ranging from sensor array monitoring and device characterization through to low-coherence interferometry