金刚石在太赫兹电真空器件中的应用

金刚石材料具有低的介电常数、小的微波损耗、良好的导热性能,成为太赫兹电真空器件发展过程中非常有研究价值和应用价值的材料。它可以作为输能窗的介质窗片和高频结构的介质支撑材料。本文介绍了微波等离子体化学气相沉积(MPCVD)金刚石材料在太赫兹电真空器件中的具体应用实例,以及在W波段行波管中的实际应用情况,包括MPCVD金刚石的制备过程,及其与金属材料的封接工艺。研制出的W波段金刚石窗冷测结果显示其在75 GHz-110 GHz频段内性能良好:驻波系数(VSWR)≤1.5,传输损耗≤0.5 dB。这种窗已经成功用于W波段折叠波导连续波与脉冲行波管中。     

铁氧体金属化技术在微波介质器件中的应用

提出一种铁氧体金属化方法,解决了微波介质器件中铁氧体容易脱落的问题,为微波介质器件的发展开辟了一个新的方向。     

Ba(B'1/3 Ta2/3)O3微波介质陶瓷的研究进展

微波介质陶瓷是制作微波器件的关键材料。具有复合钙钛矿结构的Ba(B'_1/3 Ta_2/3)O₃(B'=Mg、Zn)型微波介质陶瓷在微波毫米波频率下具有较高的品质因数,是现代微波通信技术中被广泛应用的微波陶瓷材料。文中介绍了近年来此类微波介质陶瓷的发展与研究现状。     

铁氧体金属化技术在微波介质器件中的应用

提出一种铁氧体金属化方法,解决了微波介质器件中铁氧体容易脱落的问题,为微波介质器件的发展开辟了一个新的方向。     

一维等离子体光子晶体微波传输特性研究与调控

利用基于有限元方法的COMSOL软件,仿真研究了由等离子体放电微管阵列组成的一维光子晶体的微波传输特性,讨论了微管中等离子体密度和阵列周期结构参数对一维等离子体光子晶体微波传输特性的调控作用。研究结果为微波段多通道滤波器以及动态微波器件的设计和制作提供了理论参考。     

聚酰亚胺在微波GaAs FET中的应用

聚酰亚胺是一种高分子聚合物材料。它的组分及结构使其具有比SiO_2等无机介质更优越的介质特性与热特性,且刻蚀方法简便。在微波GaAs FET中作表面钝化、双层布线隔离介质应用时明显提高了器件可靠性,尤其改善了塑料封装器件的防潮性能,简化了FET工艺步骤。     

微波介质振荡器,锁相振荡器原理与维护

1引言介质谐振器是一种高介电常数（v=36～70）、低损耗的介质材料制成的谐振器，它具有体积小、在微波电路中应用简单、性能优良等特点。应用介质谐振器（DR）可以设计出一种频率稳定性好、Q值高和噪声低的新型微波振荡源，这种振荡源称为介质谐报器振荡器（DRO），其主要优点是频率稳定度高、噪声小、体积小、结构简单、价格低、对机械振动和电源瞬变过程不敏感，因而广泛应用于通信系统、雷达信标、电子对抗接收机、导弹应答机、专用测试设备以及气象雷达设备中。2微波介质振荡器工作原理介质谐振器与覆盖微波频数的各种有源器件一起…     

Cantor分形R分集分层介质的逆散射方法

Cantor分形R分集分层介质是一种自相似结构,这种结构在光学、量子力学领域很可能有重要应用。本文根据时域信号流图技术研究这种分形结构的逆散射方法,即利用已知的反射系数谱重建Cantor分形的维数及其自相似结构。文中给出了具体重建实例。     

太赫兹传输波导器件研究进展

随着太赫兹技术的发展,太赫兹传输波导器件的研究成为待解决的重要问题之一。太赫兹波位于微波与红外光之间,寻找高效的传输、耦合器件一直是研究人员的目标。主要介绍了太赫兹传输波导研究现状,并总结了各类型太赫兹波导的优势与不足。根据材料与结构分别对金属波导、介质波导的研究进展进行了分析。其中金属波导包括裸金属线波导、微结构波导、空芯波导以及平板波导,介质波导包括介质空芯波导、多孔芯波导以及微结构波导。最后分别对太赫兹传输波导未来需要解决的研究方向进行了展望。     

天线馈电与馈电设备

0620153周期性结构在毫米波波导同轴转换中应用[刊,中]／周焱／／北京航空航天大学学报．-2006,32(4)．-412- 416(L)波导同轴转换连接器是微波、毫米波通信和测试中非常重要的器件。基于PBG和阶梯阻抗变换结构在导波系统中对电磁波传播性能的影响,探讨和研究了将这2种周期性结构应用在8mm波导同轴转换连接器的设计中的情况,通过在同轴腔内导体介质支撑垫中布置二维PBG结构抑制同轴部分横向溢散的电磁波,通过在波导腔体内增加阶梯阻抗结构,改善阻抗变换效率,提高波导同轴转换器件的传输性能。参10     

Electromagnetic reflection and transmission from a new version of Cantor fractal nonlinear multilayers

In this paper, we put forward a new version of Cantor fractal multilayers, which are nonlinear medium, and investigate its properties of reflection and transmission when a plane wave is obliquely incident upon it. A new exact self-similarity algorithm that make use of the self -similarity of these structure are developed. The results for different stages of fractal growth within the first-order nonlinear approximation are found. Compared with the traditional chain-matrix approach, the scheme provides the reflection and transmission coefficients for any stage (S) with much less calculation time on a personal computer.     

Wavelet analysis of transients in fractal superlattices

Fractal superlattices are designed by alternating dielectric layers according to an iterative fractal process. The discrete self-similarity of such stratified structures can be remotely detected from interrogation by an incident pulse. In this paper, the impulse response of one-dimensional Cantor superlattices is computed and the wavelet transform is applied to the reflected signal in order to explore its temporal distribution of singularities. For a sufficiently narrow pulse, the skeleton of the wavelet-transform modulus-maxima exhibits a hierarchical structure that makes apparent the iterative process governing the construction rule of the interrogated fractal superlattice and its geometry. In the reflected signal, such hierarchy reveals the existence of singularities that are distributed on the governing Cantor set. Finally, the similarity dimension is extracted from reflection data and a strategy for estimating the stage of growth is developed     

A Novel Bandpass Filter Made of the Microstrip with Cantor Substrates

In this paper, the microstrip line with fractal Cantor distributing substrates is investigated. Transmission matrix method is used to calculate the transmittance and reflectance. Comparing with periodic distributing substrates, the microstrip line with fractal Cantor distribution shows sharp resonances inside band gap. The resonances in somewhere split and form more peaks with increase of the number of generation. Based on the microstrip line with Cantor substrates, a novel bandpass filter is proposed. The filter has 8.8 % 3dB bandwidth and two transmission zeros, 0.27dB insertion loss. The effect of width of microstrip line and thickness of substrate on the filter properties are discussed too.     

分形光栅的散射

本文根据菲涅尔-基尔霍夫理论,研究了均匀Cantor集分形和Sierpinski地毯(carpet)分布光栅结构的电磁(光)散射,计算了一维和二维分形光栅散射的强度分布,分析了它们的空间频率分布特性.其数值结果表明,它们均具有明显的分形特征和频率选择特性.     

Theoretical analysis of a fractal surface radiation

We compare, in this paper, the far field radiated by two fractal distributions of current. The first one is obtained by a fractal cut following the Cantor arrangement, the second one keeps the length of each previous current element, but modifies the distance between the elements which is now taken as a constant. We establish the analytical formulations of the far field at any step n of the Cantor set. Then, we extract the array factor and we analyse and compare the following properties : convergence of the radiation pattern, wide of the main lobe, side lobes level and directivity.     

An efficient recursive procedure for evaluating the impedance matrix of linear and planar fractal arrays

The self-similar geometrical properties of fractal arrays are exploited in this paper to develop fast recursive algorithms for efficient evaluation of the associated impedance matrices as well as driving point impedances. The methodology is demonstrated by considering two types of uniformly excited fractal arrays consisting of side-by-side half-wave dipole antenna elements. These examples include a triadic Cantor linear fractal array and a Sierpinski carpet planar fractal array. This class of self-similar antenna arrays become significantly large at higher order stages of growth and utilization of fractal analysis allows the impedance matrix, and hence the driving point impedances, to be obtained much more efficiently than would be possible using conventional analysis techniques.     

Super Narrow Bandpass Filter Using Fractal Cantor Structures

In this paper, we present a new photonic crystal structure, which is composed of fractal Cantor multilayer with a defect embedded in its middle. Optical transmission matrix method is used to calculating the transmittance and reflectance. Compared with general Cantor multilayer, we find the new structure has wider stopband and shows a super narrow band in the middle of wider stopband. It can be served as a super narrow bandpass filter. The pass band obtained can be less than 0.6nm near the infrared 1530 nm. The optical transmission is the center wavelength is higher than 99 %. This means a very low insert loss. It is more superior to other kind narrow band filters. This kind of photonic crystal super narrow band optical filter may find applications in super dense wavelength division multiplexing for optical communications and precise optical measurement.     

Study of electromagnetic waves diffraction by bi-dimensional fractal structures using the renormalization method

The analysis of fractal structures by conventional methods gets harder and harder when the number of length scales rises. In this study, we try to combine the renormalization method and the surface impedance model to help rigorous studying of electromagnetic diffraction of fractal structures at their final (infinitum) iteration. As an application, we applied the method to a couple of fractal structures: Cantor Iris 1D and 2D.     

微波加热装置打火问题的电磁仿真

以某型号微波加热装置为代表,根据传输线多重反射原理和小反射原理,提出了一种改善微波加热装置打火问题的新方法:首先对微波传播路径上的波导管结构进行优化,研究微波加热装置波导管结构参数对每一阶段反射系数的影响,找到影响每一阶段反射系数的最优参数,组成一个反射最小的波导管结构,再利用凸包对微波加热装置的整体阻抗进行匹配,从而达到改善微波加热装置打火问题的目的。进一步的测试研究证实了该方法对微波加热装置打火问题改善的有效性。