【作者】 夏祖学；

【导师】 刘长军；

【作者基本信息】 四川大学 ， 无线电物理， 2005， 硕士

【摘要】 微带滤波电路由于具有体积小、重量轻、频带宽和易于共形等特点,但损耗较大,功率容量小,因而主要应用在小功率的微波系统中。与低频滤波器相区别,微带滤波器的主要特点之一就是其尺寸可与波长相比拟。因而当波长变化时,它必然表现出周期特性。 论文结合国内外微带线数值仿真的发展趋势,利用计算机仿真,包括时域有限差分法(FDTD)和基于频域的有限元法(FEM),对微带线进行了计算机仿真。在此基础上,对微带滤波器:低通、带阻、带通滤波器进行了计算机仿真,得到了频带宽度、带外响应等滤波电路特性,将计算结果与理论值、实验数据做分析与比较。本论文针对目前微带器件数值仿真中存在的一些问题,在仿真过程中对微带线滤波器的模型建立、激励设置、计算效率等问题都做了较为详细的描述,具有一定的工程指导意义。 时域有限差分法具有一次时域计算代替频域上逐点计算等优点,但计算精度较差,效率较低,时域有限差分法在微带线PBG结构的时域仿真方面具有独特的优势。有限元法采用自适应网格剖分和子网格技术,对于处理包含复杂形状和非均匀媒质的问题,仿真准确、计算效率高,因此具有较高的应用前景。 本文介绍了具有频率选择特性,易于加工的电磁带隙(EBG)结构。本文仿真并实测了在接地板上周期性的蚀刻方孔的EBG结构,获得了较宽的阻带,可以用来克服滤波器的周期性的副响应,仿真和实测的结果吻合的较好。本文仿真了PV-EBG结构,获得了较窄的阻带。EBG结构由于插入损耗小,比普通微带具有更高的Q值,因而适用于滤波器。更多还原

【Abstract】 Microstrip line filters have some advantages such as small size, lightweight, broad frequency band, easy to form and so on, but it still owns shortcomings, such as high loss, power limitation, and so on. One of the principal characters of microwave line filters is that its geometric size is comparable to the relevant wavelength. When wavelength varies, microwave filter is inevitable to behave the periodic character.Simulation in this paper by FDTD and FEM based on frequency domain are presented to simulate microstrip line structures. On the basis of those, microstrip line filters like microstrip line low pass, band stop, band pass filters are simulated to achieve some important parameters, such as frequency bandwidth, correspondence of stop band. By comparison of measured data with the theoretic analysis and the simulated data, the feasibility of using those software to simulate microstrip line filters are discussed. In this thesis, the problems such as defining model, defining stimulation, computational time and others which exist in solving those problems in stimulating microstrip such as the difficulties in defining models, the difficulties in defining stimulation, inefficient computation and so on are described. What the thesis has done can guide the engineering design to some extent.Up to now, FDTD has the advantages in simulation, such as computation once in time domain to replace many times computation in frequency domain. However, low precise and efficiency are shortcomings of FDTD method. FDTD has the distinct advantages in simulating micriostrip PBG structure in timedomain. While FEM adopt adaptive gridding mesh and sub-gridding technology, it is easily to deal with complicate structure and inhomogeneous medium. FEM has the advantages like more accurate simulating and higher computation efficiency. So FEM has higher engineering prospect.Due to their unique frequency selective characteristics and small compact and easily to do PCB board, EBG structures are introduced. The traditional EBG filters, also called photonic bandgap filters, are periodic structures in the floor or in the dielectric capable of prohibiting the propagation of electromagnetic waves within a certain band of frequencies. So the EBG structure is proposed, simulated and measured to get wide stopband to overcome the periodic accessory correspondence. A good agreement between the simulated and measured results was achieved. The PV-EBG is simulated to get narrow stopband. The EBG structures have lower loss and higher Q than normal microstrip filters, so they are suitable for filters.更多还原