A mechanically coupled MEMS filter with high-Q width extensional mode resonators

This work presents a novel radio frequency(RF)narrowband Si micro-electro-mechanical systems(MEMS)filter based on capacitively transduced slotted width extensional mode(WEM)resonators.The flexibility of the plate leads to multiple modes near the target frequency.The high Q-factor resonators of around 100000 enable narrow bandwidth filters with small size and simplified design.The 1-wavelength and 2-wavelength WEMs were first developed as a pair of coupled modes to form a passband.To reduce bandwidth,two plates are coupled with aλ-length coupling beam.The 79.69 MHz coupled plate filter(CPF)achieved a narrow bandwidth of 8.8 kHz,corresponding to a tiny 0.011%.The CPF exhibits an impressive 34.84 dB stopband rejection and 7.82 dB insertion loss with near-zero passband ripple.In summary,the RF MEMS filter presented in this work shows promising potential for application in RF transceiver front-ends.

A tunable dual-narrowband band-pass filter using plasma quantum well structure

A tunable dual-narrowband pass-band filter is designed. A one-dimensional photonic crystal （1D PC） is comprised of alternate dielectric layer and vacuum layer. Two quantum wells （QWs） as defects can be constructed by sandwiching two plasma slabs symmetrically in the 1D PC, and a dual-narrowband pass-band filter is formed. The conventional finite- difference time-domain （FDTD） method and piecewise linear current density recursive convolution （PLCDRC）-FDTD method are applied to the dielectric and plasma, respectively. The simulation results illustrate that the dual-narrowband frequencies can be tuned by changing the plasma frequency. The pass band interval and the half-power bandwidths （-3-dB band widths） are related to the space interval between two QWs.

New Kalman Filtering Algorithm for Narrowband Interference Suppression in Spread Spectrum Systems

A new Kalman filtering algorithm based on estimation of spread spectrum signal before suppression of narrowband interference （NBI） in spread spectrum systems, using the dependence of autoregressive （AR） interference, is presented compared with performance of the ACM nonlinear filtering algorithm, simulation results show that the proposed algorithm has preferable performance, there is about 5 dB SNR improvement in average.

高精度光谱特性测试与表征系统

针对分光光度计存在发散角而导致窄带滤波器测试存在误差的问题,研制了高精度光谱特性测试与表征系统。分析了光束入射的锥角效应以及发散角对窄带滤波器中心波长、峰值透过率和半高宽的影响。利用发散角小的激光光束作为光源,搭建了高精度光谱特性测试与表征方案,完成了窄带滤波器的精确光谱特性测试及表征。通过对中心波长532 nm窄带滤波器的制备和测试,验证了系统的实用性。测试窄带滤波器的半高宽为0.79 nm,峰值透过率为87.23%。对比5°和10°下的光谱透过率曲线,验证了角度对窄带滤波器的影响。高精度光谱特性测试与表征系统有效实现了窄带滤波器的高精度测试。

一种稳健的窄带反馈型主动噪声控制系统

传统窄带反馈型主动噪声控制系统采用并型自适应滤波器结构,用于合成参考信号时,仍存在参考信号合成质量较差、滤波器权值的初值设置难度高、应对非平稳窄带噪声的能力不足等问题。为解决以上问题,通过引入高效的串并型自适应滤波器结构来合成参考信号,提出新型的窄带反馈型主动噪声控制系统,改善参考信号合成质量,进而提升系统的整体降噪性能。新型系统不仅有效解决了传统系统存在的参考信号合成质量较差的问题,还降低了滤波器权值的初值设置复杂度,同时还提升了系统应对非平稳窄带噪声的能力。实验结果表明,新型系统较传统系统的前后两部分的降噪量分别提升了7.89和9.18 dB。仿真和实验结果共同验证了提出的系统较传统系统具有更强的稳健性和降噪性能。

Capacitive Coupled Wide-Notch Stepped Impedance Narrow-Band Bandpass Filter for WiMax Application

The development of wireless communication standards necessitates optimal filter design for the selection of appropriate bands of frequencies.In this work,a compact in size pair of parallel coupled symmetric stepped impedancebased resonator is designed with supporting to the WiMAX communication standards.The coupled resonator is tuned to allow the frequency band between 3.4 GHz and 3.8 GHz,which is centered at 3.6 GHz.A parasitic effect of capacitively coupled feed structure is used for exciting the two symmetrical stepped impedance resonators.The bandwidth and selectivity of the filter are enhanced with the change of characteristic impedances and controlling the coupling gap between resonators.This design offers single narrow sharp passband selectivity as well as multiple stopband harmonic suppression arising as a result of multiple transmission zeros.The designed filter operates with a fractional bandwidth(FBW)of 11.47%.The proposed single narrowband bandpass filter provides better suppression in either side of the tuned frequency(3.6 GHz)without degrading the passband performance.Also,this novel filter offers an insertion loss of about−0.08 dB and a return loss of greater than−30 dB in passband.This approach is useful for eliminating unwanted spurious harmonics responses that enter the desired response.The suggested bandpass filter has been simulated using Advanced Design System(ADS)tool,and the measurement has been made using a network analyzer,and the results are reported.

Compact Narrow Band Non-Degenerate Dual-Mode Microstrip Filter with Etched Square Lattices

A compact narrowband non-degenerate dual-mode microstrip filter with square shape cuts is presented. The structure is developed by loading the conventional non-degenerate dual-mode resonator by open circuit stubs at two opposite corners. The filter bandwidth is controlled by only decreasing the higher cutoff frequency of the conventional type. With Square shape cuts, return loss is improved. A 20% fractional bandwidth filter is designed and implemented on FR4 material with 4.4 dielectric constant and 1.6 mm thickness at center frequency of 1.5 GHz with passband of 1.3 GHz to 1.6 GHz. Analysis has been achieved using the IE3D simulator. Experimental results do agree with simulations.

Development of Hexagonal MMR Based UWB Bandpass Filter with 5 GHz Notch Band

This paper presents an experimental verification of ultra-wideband bandpass filter (BPF) for UWB applications and notch filter in order to suppress 5 GHz narrowband service when it coexists with UWB radio system. The BPF consists of a hexagonal shaped multiple mode resonator (MMR) with interdigital coupling at both sides. Notch filter is derived from BPF by introducing four embedded open stubs near by the MMR. The developed BPF has insertion loss of –2 dB and the minimum return loss about –35 dB, while for the notch filter they are –3 dB and –40 dB respectively. The group delay obtained for bandpass filter is below 0.2 ns and for notch filter, it is about 0.3 ns. With the above structural features the overall dimensions of the filter is 38 mm (length) × 3.2 mm (breadth) × 1.6 mm (height) and the percentage fractional bandwidth (FBW) of the proposed filter is about 120.48%.

BER of OFDM System with Multiple NBI Rejection Cascade Complex Coefficient Adaptive IIR Notch Filter

In this paper, rejection of multiple narrowband interferers in a binary phase shift keying modulated orthogonal frequency division multiplexing (BPSK-OFDM) system is investigated. The BPSK-OFDM system in consideration operates in an additive white Gaussian noise (AWGN) channel. A cascade complex coefficient adaptive infinite impulse response (IIR) notch filter with gradient-based algorithm is used to reject the interferers. Bit error ratio (BER) performance of the system is studied and a general closed-form expression is derived assuming negligible steady-state leakage NBI and by estimating the decision variable as Gaussian distributed based on Central Limit Theorem (CLT). Dependence of the BER performance on the notch bandwidth coefficient is demonstrated by the analysis. Extensive simulation results are included to substantiate accuracy of the analysis.

多通道卫星导航探空接收机射频前端的设计与仿真

结合卫星导航探空系统的发展需要,为实现卫星导航探空系统实时跟踪多个探空仪,使用EDA软件设计对多通道卫星导航探空接收机射频(RF)前端进行仿真。内容包括功率分配器、低噪声放大器和滤波器3种元器件与射频链路的级联仿真。信号经功率分配器变为多通道信号,不同通道使用不同解码方式可实现同时跟踪多个目标。仿真结果表明,方案可实现良好的物理多通道效果,解决了射频放大器芯片阻抗不匹配问题,实现了2.5%带宽超窄带滤波。

基于UV-LIGA工艺的超窄带毫米波三频带通滤波器

针对当前6G无线通信系统对3 mm毫米波器件的需求急速增加,为了提前应对在这一频段的通信协议划分,利用金属谐振腔和矩形波导设计出一款中心频率为102.03 GHz的单频带通滤波器。然后,基于多模传输理论将其优化为一款中心频率分别为96.83和106.31 GHz的单通道双频带通腔体滤波器。采用交叉耦合的方式引入传输零点,设计出一款在98~105 GHz的工作范围内,具有98.49、99.79和104.20 GHz三个中心频率的超窄带三频带通腔体滤波器,其3 dB相对带宽分别为0.32%、0.63%和0.30%。采用基于SU-8负性光刻胶的UV-LIGA工艺对样品进行加工,并使用搭建的W波段电磁性能测试平台完成对样品射频性能的测试,测试结果与仿真结果具有良好的一致性。

移动感知的NB-IoT无线电资源配置方法

窄带物联网(NarrowBand Internet of Things,NB-IoT)是实现万物互联重要的通信技术,其为了扩大通信覆盖范围和提高可靠性而牺牲了时延等性能指标,且难以动态适应移动物联网设备.对此,本文提出了一种适用于移动设备的NB-IoT无线电资源配置方案.该方案通过卡尔曼滤波对物联网设备的移动位置进行预测,建立数学模型对通信可靠性进行估计,开展了块误码率、时延、能耗等性能指标的量化分析,并提出了无线电资源配置的优化模型和方法.本文基于真实数据集开展了仿真实验,对该方案的有效性进行了验证,实验结果显示该方案能保证移动物联网设备与基站连接的同时降低时延.

基于遗传算法的斜入射窄带滤光片膜系优化设计

根据薄膜窄带滤光片在斜入射时的偏振特性,提出了基于遗传算法的斜入射薄膜窄带滤光片膜系优化设计方法.根据开发的程序,设计并制备了一组可用于18°倾斜入射的0.8纳米信道间隔的五腔薄膜窄带滤光片.该滤光片能有效地抑制斜入射时偏振光中心波长的分离现象,降低器件的偏振相关损耗,通过角度调谐能实现选择波长的改变.通过与针法设计的滤光片膜系相比,遗传算法得到的膜系具有更高的矩形度、更大的波长调谐范围以及更低的偏振相关损耗.实验结果表明其满足设计要求并有超过25纳米的波长调谐范围.

新型小尺寸窄带偏振分光器在光纤通信中的应用

在光纤通信中,为了在不改变调制波长范围的基础上仍能实现更多数据通道的波分复用,设计了一种新型的小尺寸窄带偏振分光器,用于对现有的数据通信网络进行扩容以及提高光信号的信噪比。在该分光器上蒸镀了两种新设计的膜系,一层是窄带滤光膜,另一层是偏振分光膜。采用TFCalc软件仿真,设计结果中窄带滤光膜的带宽约为0.4nm,偏振分光膜在1 530~1 560nm范围内对p光的通透性能优于99.8%。基于以上膜系设计在BK7光学玻璃上实际制备两组膜系,实验采用Agilent 8164-A型光波测量系统对经过膜后的光进行光谱分析。结果显示,窄带滤光膜的实际带宽优于0.4nm,增益平坦度小于-0.05dB,相比现有常见的0.8nm滤光膜具有更窄的带宽,可以实现在调制波长范围不变的条件下增大波分复用的数据通道总量。偏振滤光膜的实际p光透光率为99.6%,相比仿真值略低,但仍优于设计要求,相比传统分光器的光信号强度保留效果更好,具有更高的信噪比。综上所述,该分光器具有更好的应用价值和实用意义。

水声信号的窄带滤波研究

研究一种用于有色噪声背景下接收水声信号的窄带滤波方法。它用白化滤波器实现有色噪声的匹配滤波。该滤波电路具有优良的选频能力,抗干扰性强,功耗极低,较好地解决了水下信息传输中存在的通道之间频率间隔小、信号微弱、易受噪声干扰、用电池供电而要求工作时间长等问题。采用这种窄带滤波方法的水声接收机具有结构简单、性能稳定、对弱信号检测能力强等优点,增大了定位声纳的作用距离。

高斯光束斜入射窄带滤光片的透射光强分布

基于多光束干涉原理,推导了高斯光束斜入射角度调谐窄带滤光片后的透射光强表达式.在此基础上研究了入射角对高斯光束的透射特性的影响.计算和实验结果表明:随着入射角的增大,透射光强的光斑会出现一定程度的展宽现象;当入射角度较小时,输出为单一光斑,但其光强峰值位置产生了一定的偏移,并不在呈现高斯分布;当入射角度较大时,输出则为一系列的离散光斑.

角度调谐滤光片特性分析及膜系设计

对窄带滤光片的倾斜入射特性作了分析.斜入射时其透射通带和峰值会向短波方向移动,透射曲线的稳定性跟滤光片的间隔层结构相关,多腔间使用相同的间隔层可以保证斜入射时有稳定的峰值透射率和带宽,利用该特点可以制备角度调谐窄带滤光片.透射光S和P偏振分量的中心波长随入射角度的增大出现分离现象,产生较大的偏振相关损耗.通过搭配不同厚度的高低折射率材料作为间隔层,改变其有效折射率,使其两个偏振分量的中心波长实现重合.设计了符合密集波分复用(Dense Wavelength Division Multiplexing,DWDM)系统要求的低偏振相关损耗四腔窄带角度调谐滤光片膜系,其可调谐范围达20nm以上,并评估了所设计角度调谐滤光片的调谐性能.

基于能量比预处理的FFT窄带滤波方法

分析了有效信号和窄带干扰在频域上的缓变和突变的特点,提出了一种基于能量比预处理的改进FFT窄带滤波方法.利用功率谱信号一个时间窗内的前后能量对比将原低于有效信号的窄带干扰进行放大,为FFT窄带滤波的阈值的确定打下基础.对于超过阈值的窄带干扰信号,在频域处理时采用对有效信号保持原数值、干扰信号进行压缩的处理方法,防止了由于滤波而造成的信号的畸变,达到了保留信号特征的目的.处理结果表明,时间窗取8~10个记录点,阈值系数取0.3~0.4,任何原始信号的信噪比都能取得较好的滤波效果.

DDS频率合成器杂散的PLL抑制

DDS频率合成器由于其固有的数字特征,使得输出信号中存在大量的杂散,杂散的抑制一般通过输出端的低通或带通滤波器来进行,但效果较差。PLL具有良好的窄带和跟踪特性,文中提出了基于PLL的窄带滤波器杂散抑制方法。利用ALTERA公司Dspbuilder工具箱实现的DDS进行仿真,通过输出信噪比的比较,验证了该法的正确性。

窄带多通道滤光片的设计与制备

介绍了三种获得窄带多通道滤光片的方法。第一种方法是具有缺陷的多异质结结构,该结构能够展宽光子晶体的禁带同时实现多通道效应。第二种方法是多通道导模共振布儒斯特滤光片,此类滤光片可以采用单层膜结构来实现多通道效应,也可以采用具有相等折射率的双层膜结构来实现多通道效应。第三种方法是组合刻蚀法制备窄带滤光片列阵。该方法不仅可以制作单腔窄带滤光片列阵,还可以制作双腔窄带滤光片列阵。窄带多通道滤光片在光学领域中具有一定的应用前景。