摘要：微波滤波器是射频微波电路的关键器件，在通信技术高速发展的现代社会，微波器 件正向小型化、高集成化的方向发展。因此在保证器件性能的同时尽量减小器件的尺寸 十分重要。本文针对 X 波段通道接收机的需求开展了 X 波段微带带通滤波器的设计和优 化，主要工作包括： 

(1)明确滤波器的设计要求，选用发夹型结构。充分了解发夹滤波器的工作原理和一 般设计流程。 

(2)通过在输入输出端口并联开路分支来抑制寄生通带，在非相邻谐振单元间添加二 分之一波长线来改善滤波器选择性。并且采用渐进抽头线避免连接处的不匹配情况，设 计了五阶发夹滤波器。9.2-11.2GHz 通带内插损优于 1.13dB，回损基本优于 18.5dB；不 仅削弱了 19-21GHz 的寄生通带，还实现了 6-9GHz 带外抑制基本大于 20dB，12-14GHz 带 外抑制大于 30dB。 

(3)通过改变对称谐振单元的参数，耦合不同的谐振单元，设计出七阶发夹滤波器。 通带内插损优于1.68dB，回损优于20dB。寄生通带抑制大于20dB，6-8GHz、12-14GHz频 段带外抑制大于50dB。 

相比于文献[5]的X波段LTCC双模滤波器，本文的五阶发夹滤波器低于中心频率2GHz 处带外抑制改善了6dB，七阶滤波器距离中心频率约2GHz处带外抑制改善了30dB。 

关键词 X 波段  带通滤波器  微带线 发夹滤波器

毕 业 设 计 说 明 书 外 文 摘 要

Title     The X-band Microstrip Filter Design             

Abstract：Microwave filters are vital devices of radio frequency microwave circuits. Currently, with the rapid development of communication technology, microwave devices are developing towards the direction of miniaturization and high integration. It is important to minimize the size of devices while ensuring the performance of them. This paper researches the design and optimization of the X-band microstrip bandpass filter, which is needed in the X-band receiver. Here are main parts of this paper. 

(1)Specify the required goals of the filter, choose the type of hairpin filter. Fully understand the working principle of hairpin filters and general design process. 

(2)Microstrip lines of a quarter wavelength are used in both input and output of the filter to inhibit the parasitic band. A microstrip line is also added between non-adjacent resonators to improve the selectivity. Also, it applies progressive tapping line to avoid the mismatch of joints. The pass band of fifth-order filter ranges from 9.2GHz to 11.2GHz. The insertion loss within pass band is better than 1.13dB and its return loss is better than 18.5dB. The parasitic band, whose frequency range covers 19GHz to 21GHz, can be weakened by using the open-circuit branches. The suppression within 6-9GHz is greater than 20dB, and that of 12-14GHz is greater than 30dB. 

(3) The seventh-order hairpin filter is designed by changing the parameters of symmetrical resonators and coupling different resonators. The insertion loss is better than 1.68dB and the return loss is better than 20dB.The parasitic band is reduced by 20dB. The suppression within 6-8GHz, 12-14GHz is better than 50dB. 

Compared with the X-band dual-mode LTCC filter of reference [5], the fifth-other hairpin filter of this paper acquires improvement of suppression by 6dB at about 2GHz lower than the center frequency. The suppression of the seventh-order filter is improved by 30dB at about 2GHz from the center frequency. 

Keywords   X band，bandpass filter，microstrip line，hairpin filter 

目次

1    引言1 

1.1    研究背景1 

1.2    国内外研究现状1