带阻滤波器英文翻译.doc

安徽建筑大学 毕 业 设 计 (翻 译) 专 业 通信工程 班 级 10通信①班 学生姓名 高路 学 号 10205040109 指导教师 吴东升 2014年6月6日 Microwave filters Microwave Engineering Pozar A filter is a two-port network used to control the frequency response at a certain point in an RF or microwave system by providing transmission at frequencies within the passband of the filter and attenuation in the stopband of the filter. Typical frequency responses include low-pass, high-pass, bandpass, and band-reject characteristics. Applications can be found in virtually any type of RF or microwave communication, radar, or test and measurement system. The development of filter theory and practice began in the years preceding World War II by pioneers such as Mason, Sykes, Darling, Fano, Lawson, and Richards. The image parameter method of filter design was development in the late 1930s and was useful for low-frequency filters in the radio and telephony. In the early 1950s a group at Stanford Research Institute, consisting of G.Matthaei, L.Young, E.Jones, S.Cohn, and others, became very active in microwave filter and coupler development. A voluminous handbook on filters and couplers resulted from this work and remains a valuable reference [1]. Today, most microwave filter design is done with sophisticated computer-aided design (CAD) packages based on the insertion loss method. Because of continuing advances in network synthesis with distributed elements, the use of low-temperature superconductors and other new materials, and the incorporation of active devices in filter circuits, microwave filter design remains an active research area. We begin our discussion of filter theory and design with the frequency characteristics of periodic structures, which consist of a transmission line or waveguide periodically loaded with reactive elements. These structures are of interest in themselves because of their application to slow-w