Design and fabrication of a novel resonator for resonant accelerometer

A novel resonator for accelerometer with sensing and actuating combs was designed and fabricated based on micro electromechanical system (MEMS) process. Driving force and demand voltage of the resonator were analyzed by analytical method and Finite Element Method (FEM). Sensing capacitance on resonance state and Q factor under atmosphere was calculated by these two methods. The micro fabrication process was planned and realized using MEMS (Micro electromechanical System) method. The testing results show the performance of the resonator is high; the natural frequency of the resonator is 54 523.5 Hz, which has the error of 13.6％ with the theorical value.     

INFLUENCE OF PUMPING POWER CHANGE ON CW Nd:YAG LASER

This paper presents that pumping power change of Nd: YAG laser will induce not only gain change but also loss change. As a result, it induces oscillating mode change, laser cavity unstable, and the complicated change of laser output power. On the basis of a large theoretical calculation and experimental support, the paper shows that the plane-parallel cavity is more suitable for the multimode operation and the plane-convex or concave-convex cavity for the single mode operation     

基于微波技术的温室作物含水量检测

为适应现代温室大棚灌溉系统科学化与精量化的需求,提出一种基于微波谐振技术测量温室作物含水量的方法。论述利用微波谐振法测量作物含水量的原理,将温室蔬菜叶片作为检测对象,提出并论证作物叶片水分含量不受叶片密度影响的算法。通过作物叶片介电常数作为桥梁,建立起作物含水量与谐振腔谐振频率f0与品质因数Q的函数关系,得出关系曲线,为建立温室大棚含水量检测系统打下基础,也为精量灌溉系统水分指标的获取提供一种新的技术手段。     

响沙,沙响与共鸣箱之奥秘

本文通过国内外学者对响沙的研究、试验和学说，提出了响沙和沙响的区别，在２０年前作者提出“共鸣箱”理论的基础上，进一步阐释了特殊地貌对响沙形成的机理。     

基于 CSRR-HMSIW 和紧凑型短路CRLH-TL 谐振器的双带滤波器研究

提出了一种基于半模基片集成波导加载互补开口谐振环（CSRR‐HMSIW）和紧凑型短路复合左右手传输线（CRLH‐TL）谐振器的新型双带滤波器设计方法．根据CSRR‐HMSIW结构的传输特性和短路CRLH‐TL结构的色散特性,找到一种CSRR‐HMSIW和短路CRLH‐TL结构间的结合方式．精确设计CSRR的边长,确定CSRR‐HM‐S IW谐振器的谐振频点,在低频段实现以该谐振点为中心频点的第一个通带;精确设计短路复合左右手叉指长度,确定短路CRLH‐TL结构的谐振频点,实现以该谐振频点为中心的第二个通带,同时利用两短路CRLH‐TL间耦合进一步增强第二通带的传输特性和抑制特性．设计了两个通带的中心频率分别为2.25 GHz和2.97 GHz ,实测插损小于1.9 dB和带外抑制达到25 dB以上,测试与模拟仿真结果基本一致．     

测量谷物颗粒湿度的微波谐振腔法初步研究

介绍一种测量谷物颗粒湿度的微波谐振腔法及其原理和装置,以及它的测量过程和研究的实验结果。实验研究证明,微波谐振腔技术用来测量黄豆颗粒的湿度是一种有价值的方法。当腔用黄豆颗粒加载时,测量的是谐振频率和传输系数的改变值,所以,对测量系统的稳定性要求不太苛刻。这一测量技术也可以用来测量稻谷、麦子及其它种籽的湿度。     

A novel substrate integrated waveguide broadband bandpass filter

A novel broadband substrate integrated waveguide bandpass filter is presented based on the highpass characteristics of substrate integrated waveguide (SIW) and the bandstop performance of photonic band gap (PBG) structure.In order to verify it,a wideband bandpass filter with center frequency of 5.0 GHz and fractional bandwidth of 60% is designed.The electromagnetic simulation results show its good passband characteristics from 3.5 GHz to 6.5 GHz,and the maximun insertion loss is about 0.64 dB.An experimental filter prototype is fabricated with standard PCB technics and measured with the vector network analyzer.The measured results show the passband is from 3.8 GHz to 6.8 GHz,the fractional bandwidth is about 56%,and the minimal insertion loss is about 1.6 dB.The measured results are in good agreement with the simulated results.     

压膜阻尼对有孔微梁谐振器振动特性影响分析

微梁谐振器是微机电系统中常用的一种谐振器。基于修正雷诺方程和梁的振动理论,通过求解微梁的控制方程,得到了压膜阻尼对有孔微梁梁振动特性的影响,可以为器件的优化设计提供参考。     

Designing a microstrip bandpass filter with multi coupling stepped impedance resonators

A compact multi coupling microstrip bandpass filter based on microstrip stepped impedance resonator (SIR) characteristics was presented. The principle of second harmonic suppression with a proper impedance ratio was introduced, which improved the rejection at the stopband of the bandpass filter. A microstrip multi coupling SIR bandpass filter with 3.65 GHz center frequency and 3.5% fractional bandwidth was designed and fabricated. The result of simulating the filter showed -10 dB attenuation at the first harmonic center frequency, making the upper skirt deeper and the bandpass response more symmetric than filters without microstrip SIR. The experimental filter was measured and had -3.2 dB insert loss at the central frequency and a bandwidth of approximately 120 MHz. The measured result was consistent with the simulated one.