射频电调谐滤波器的研究与设计

【作者】 林彬；

【导师】 张玉兴；

【作者基本信息】 电子科技大学 ， 电路与系统， 2008， 硕士

【摘要】 面对日趋复杂的电磁环境以及变化繁多的雷达特征信号,现有的雷达侦察接收系统对多种信息的处理显得力不从心,本文从接收系统前端考虑,对其中的一种解决方法——用一个调谐频率范围宽的电调谐滤波器来替代多个固定调谐滤波器进行分析研究。这样的前端就可将系统的接收中心频率和带宽自适应到输入信号的频率和带宽,其实就是对输入信号进行一次预分选、预滤波,剔除对接收系统毫无作用的信号;同时期望能对大信号自动减小增益,对小信号增加增益,提高系统的动态范围;而且可以对干扰信号进行抑制。本文所研究的电压可调谐带通滤波器是射频选频网络中一个重要部件,它具有带宽小、中心频率调谐范围大,阻带抑制度高、频率调谐范围内带宽和滤波曲线变化很小、结构小型化等特点。在整个研究的过程中,概括起来主要做了以下几个方面的工作:1.首先从滤波器网络设计理论入手,在耦合谐振器带通滤波器的基础上,简单介绍了从低通原型滤波器到耦合谐振器可调带通滤波器的设计过程,并通过查阅大量的资料和进行公式推导得到频率变化和可调滤波器性能参数之间的关系公式。2.针对可调滤波器的设计,详细研究分析了可变电容二极管在谐振回路中的特性、介绍LC调谐滤波器的电路设计以及微带线理论。3.滤波器的设计是工作的重点,包括基本电路结构的设计、梳状线滤波器的近似等效模型,利用ADS仿真软件进行的优化设计和滤波器的测试工作三部分。前两部分工作主要是在理论设计的基础上,推算并利用软件得出实际滤波器的各个部件更精确的值。针对所设计可调谐带通滤波器调谐频率范围宽的特点,在仿真过程中采用了一些特殊的处理方法,例如改进的优化方法。第三部分的工作主要是对加工好的滤波器进行测试,并进行调试,最后分析了滤波器的某些性能不能完全满足要求存在的原因以及对该课题的后续工作开展提供一些思路。更多还原

【Abstract】 The current radar scout system has some problems for processing multiform signals,conrfonting the complex electromagnetic environment and various radar characteristic signals. The especial front-end in receiver can solve these problems,and this dissertation analyzes it. That is to say, a tunable filter which range of tunable centrofrequency is big substitutes for several normal filters. This front-end has the adaptive ability for the magnitude and frequency of input signals. It can prefilter for the input signals,eliminate the useless signals,and increase gain of small signals;decrease the gain of big signal. The dynamic range of receiver system is improved in this way.The tuanable bandpass filters presented here is an essential part of the RF frequency selection network. These filters enjoy such merits: narrow bandwidth, range of tunable centrofrequency is big, the high attenuation in the stopband ,its structure is compact and almost changeless bandwith and filter characteristics. During the course of the research, the focuses are put on the followings:1.Firstly,on the base of the theories of the network design and coupling-resonator filter design, we introduce the processes from the lowpass filter prototypes to the bandpass coupling-resonator filter, analyze the relation between the variable center frequency and the filter’s parameters by consulting, design formulas are presented.2. About the tunable filier, the varactors in the resonator and design the resonator is analyzed detailedly in this paper. Depict the design idea of the tunable amplifier.3. The emphases of the work are to design the tunable filter, including getting the approximate equivalent model of combline filter, simulation process with the help of the ADS software, and test the filter. The first part is to obtain the exactor component on the base of the former analysis. For the big tuning range of this filter, this paper adapts a special method to simulate. The second part is to test and adjust filters.Finally, the possible causes of the problems is analysed and offer ideas to the later works.更多还原