【作者】 赵娜；

【导师】 尹应增；

【作者基本信息】 西安电子科技大学 ， 电磁场与微波技术， 2007， 硕士

【摘要】 随着通信技术的发展,频率资源日益紧张,分配到各类通信频段的信道间隔越来越密,造成系统间的信号干扰越来越多。为了降低系统对信号的衰减,抑制各种干扰信号,研制带窄、体积小、带外抑制度高的滤波器等高性能无源器件成为国内外研究的热点。本文根据移动通信对滤波器的要求,研究了广义切比雪夫综合方法,设计出了应用于WCDMA移动通信频段的腔体带通滤波器。广义切比雪夫函数滤波器可以在带外实现有限个传输零点,通过在阻带任意位置处增加传输零点来提高带外的抑制性能而实现与椭圆函数滤波器相似的功能。本文的主要工作有:阐述了广义切比雪夫滤波器综合理论:对于给定的传输零点,采用循环递归技术来构成传输和反射函数多项式,并利用传输和反射多项式综合出耦合矩阵。文中详细给出了具体的公式推导过程。研究了几种常用的腔体滤波器结构,并根据本文滤波器的设计要求选用了同轴方腔来实现滤波器。根据广义切比雪夫综合方法,由给定的传输零点和回波损耗,计算了一个在高频端具有两个传输零点的滤波器实例。并与参考文献比较,结果吻合良好,验证了综合过程的正确性。根据WCDMA通信的要求,设计了一个六阶同轴方腔带通滤波器,并给出了详细的综合过程。利用综合出来的结果,结合HFSS软件对腔体滤波器进行了计算机仿真分析;利用网络分析仪进行实验研究。测试结果与实际需要的技术指标相吻合,进一步说明了本文公式推导和程序编写的可行性。滤波器的调试是滤波器设计的一个重要部分,文中对调试步骤和技巧进行了具体的描述。更多还原

【Abstract】 With the development of modern communication technologies, the Electromagnetic spectrum is limited and has to be shared; filters are used to select or confine the RF/microwave signals within assigned spectral limits. Filters play important roles in many RF/microwave applications. They are used to separate or combine different frequencies. Emerging applications such as wireless communications continue to challenge RF/microwave filters with ever more stringent requirements—higher performance, smaller size, lighter weight, and lower cost.In this paper, based on the method of generalized Chebyshev synthesis, a cavity band-pass filter is studied and designed in order to satisfy the WCDMA mobile system demands. Generalized Chebyshev filter realize the finite-frequency transmission zeros, by adding transmission zero point in stop-band arbitrarily, the characteristic of out-of band is improved and the filter have the similar function with the elliptic functions filters. The main works of this paper is following:Band-pass filter is studies based upon the generalized Chebyshev filter synthesis principle: Through recursions technique, the transfer and reflection function polynomials and coupling matrix is constructed with a return-loss level and prescribed zeros, and detailed deducing of formulations is given in this paper.Several common forms of cavity filter are introduced, and the coaxial rectangle cavity structure is chosen to meet the design requirements of the filter. With given prescribed zeros and return-loss level, an example is presented in which the calculated results agree well with the available results and the synthesized process is validated.Based on the generalized Chebyshev theory, a sixth-degree coaxial rectangle band-pass filter applied in WCDMA communication is designed and simulated by commercial software - HFSS. The experiment results show that the characteristics given by network analysis satisfy the designed requirement. The feasibility of formulation deducing and programming are further verified.Lots of tuning works must be done in filter design and the procedure is also described in the papers.更多还原