Substrate integrated folded waveguide controllable mixed electric and magnetic coupling structure and its application to millimetre‐wave pseudo‐elliptic filters

A substrate integrated folded waveguide (SIFW) controllable mixed electric and magnetic coupling structure is proposed and investigated, which is suitable for millimeter‐wave pseudo‐elliptic filter applications. The proposed structure is built by a meandered slot‐line (MSL) combined with an inductive via‐hole in a SIFW cavity, which can support two closely‐spaced resonator modes and achieves a mixed coupling. By adjusting the physical sizes of the mixed coupling structure, the electric and magnetic coupling can be separately controlled and a controllable transmission zero (TZ) can be produced below/above the passband. Furthermore, detailed analysis of the SIFW cavity mode spectrum and the mixed coupling characteristics are presented. Finally, direct‐coupled and cross‐coupled fourth‐order pseudo‐elliptic filters are designed, fabricated and measured to verify the proposed mixed coupling structure. The experimental results show that the proposed filters have good performance, such as high frequency selectivity, compact size, wide upper stopband, and easy integration with other planar circuits.     

A bandpass filter using asymmetric stepped‐impedance resonators and symmetric T‐shape interdigital capacitor structures with wide out‐of‐band rejection

In this study, a novel stepped impedance resonator (SIR) is proposed. This SIR is composed of two stepped impedance transmission‐lines and an interdigital capacitor structure. The proposed resonator has a high ratio of the first spurious frequency f_s to the fundamental frequency f₀ and is suitable to design wide stopband filters. An equivalent model is used to analyze the resonant properties of the resonator. The design guidelines of the proposed resonator are summarized. Moreover, the coupling properties of the resonator are simulated and analyzed. Finally, a small high‐temperature superconducting bandpass filter is designed and fabricated using the proposed SIRs. The stopband of the filter is extended up to 4.0 f₀ and 3.5 f₀ with 30 and 60 dB out‐of‐band rejection levels, respectively.     

条干均匀度仪波谱图算法设计与实现

条干均匀度仪的波谱图能够精确地反映出纱疵的周期性特征,从而可以快速地确定出纺纱工艺流程中故障的位置;但是如何将波谱图快速准确地实现一直是研究的难点;基于数字信号处理中的重采样定理,通过对不同机械故障所产生的纱线信号进行分析,改进了条干均匀度仪波谱图算法,该算法在需要观测的波长范围内构建了110个不同频带的带通滤波器,根据相邻滤波器频带关系分组进行波谱分析;通过DSP28335微处理器的数据采集、信号处理和上位机波谱图显示的系统进行实验,结果证明了该算法的可行性;其改进后的算法极大地减小了以往所用硬件的复杂度、提高了运算速度并拓宽了波谱图的可观测范围,且能够更精确的检测出故障位置。     

电磁带隙的超宽带阻带天线设计

设计了一种电磁带隙(EBG)结构.根据实际应用要求,在一种超宽带微带天线上加载电磁带隙单元,设计出一种阻带天线.对天线的多个参数进行讨论并优化设计,根据仿真实验制作出天线实物.实验结果说明:天线在3.11～5.97 GHz的频带范围内,电压驻波比(VSWR)值大于2;在5.46 GHz处达到了9.23的峰值,阻带范围覆盖WiMAX (3.4～3.7 GHz),C-band (3.7～4.2 GHz),WLAN(5.15 ～5.35 GHz/5.725～5.825 GHz)这三个频段,且天线增益在阻带内明显降低.     

超宽带穿墙雷达三维快速成像算法

超宽带穿墙雷达是一种能够隔墙探测和定位的新型实时成像雷达系统,在城区巷战,反恐斗争和人质救援中应用非常广泛.穿墙雷达对成像的实时性要求非常高,传统的成像算法已不能满足计算时间上的要求.本文将基于逆边界散射变换的快速成像算法应用到穿墙雷达系统中,利用FDTD数值仿真验证了对隐藏在墙后目标的三维成像结果,并分析了墙壁对目标定位误差的影响.研究表明,与传统的后向投影成像算法相比,基于逆边界散射变换的成像算法计算效率高,实时性好,且能对目标边界形状清晰成像.     

Enhanced waveguide bandpass filters using S‐shaped resonators

This article presents a new solution for stopband performance improvement of rectangular waveguide bandpass filters using S‐shaped resonator loaded waveguide configurations at microwave and millimeter‐wave frequencies. The proposed filter structure is compact in size when comparing with the standard E‐plane counterpart. Compactness is achieved by taking advantage of the properties of slow wave effect in half wavelength resonators. Periodicity is readily imposed upon cascading the S‐shaped resonators within the rectangular waveguide. The structure is simple and compatible with E‐plane technology. This type of bandpass filters can be easily realized with a single metallo‐dielectric insert within a standard rectangular waveguide. Simulation and experimental results are presented to validate the argument along with some design guidelines. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE 2009.     

Topology bandpass filters in coplanar strip lines

We report a new bandpass filter on coplanar strip (CPS) lines for RF and microwave applications. The filter is implemented as electrode topology on the CPS electrodes. The topology consists of basic electrode patterns that emulate inductors and capacitors in a two‐port filter section. In the design process, equivalent circuit model is used to identify the initial topology, which is then fine tuned using full wave analysis. The bandpass filter is very compact in size and planar in structure. It does not use quarter‐wavelength sections, vias, or bonding wires. It can be fabricated without incurring additional cost. Bandpass filters for the 2.4 GHz ISM (Industrial, Scientific, and Medical) band were designed, fabricated, and measured. The measurement responses agree well with the full‐wave simulation results. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.     

中频带通ΣΔ调制器的建模与仿真设计

中频带通sigma-delta(ΣΔ)调制器是数字中频接收机的核心模块。基于一个双采样技术的低失真四阶带通sigma-delta调制器,分析了其主要的非理想特性,并建立了模型。利用根轨迹法对该调制器进行了稳定性研究,同时在TSMC 0.18μm的工艺下给出了该调制器的电路图以及版图的后仿真结果。后仿真结果显示了建立模型的准确性,证明该模型可以有效指导后级电路设计。     

Semi-definite programming based pulse waveform design and its further analysis

In order to provide a judicious pulse waveform design required for ultra-wideband（UWB）communication to enable the UWB spectral mask compatible and coexistent with other existing wireless communication systems,a semi-definite programming（SDP）based pulse waveform design method for UWB radios is introduced and a further analysis is given in this paper.By using Sedumi and Yalmip toolboxes of Matlab,the procedure of solving the SDP problem is simplified.Simulation results show that this SDP based pulse waveform design method can be used to design pulses that fulfill the Federal Communications Commission（FCC）spectral mask strictly and optimize the power efficiency at the same time.This paper also analyzes the influences of the power efficiency duing to the changes of sampling interval and the number of combined pulses,and then the optimal sampling interval that maximizes the transmission power can be found.     

基于孤立词语音识别定位系统的研究与设计

寻找物品是生活中常见而且耗时的事情,如能发明一种设备可以快速把随手放置的物品定位出来,必将大大方便人们的生活,犹如google对互联网的意义。本系统的设计独辟蹊径,结合了模拟电路技术和语音识别技术,利用语音作为输入触发信号,实现一种低成本的适用于家庭使用的快速物体定位系统。本系统在经典的孤立词语音识别技术的基础上,对进一步增大识别距离,提高抗噪能力及提高识别能力,提出一些很实用的技术与方法,并在本系统的实现中得到较好的应用。