C波段高K微带陶瓷滤波器的设计与制作

发布时间：2018-08-07 12:03

【摘要】：身处飞速发展的通信时代,频谱资源的使用越来越广泛,也导致剩余可用空间变得更加狭小,应用于射频领域的高性能的滤波器研究成为当前热点之一。商业通信与军用通信系统对滤波器的各项性能提出了在满足常规条件下更加苛刻的一些要求:高选择性,低损耗,小型化。在军用通信技术中,特别是基于陶瓷基板制作的微带滤波器具有低插损,小尺寸,高可靠性等优点,受到了越来越多的关注。我国的陶瓷滤波器起步晚,并且国外采取了技术封锁,研究高品质的陶瓷微带滤波器具有广泛前景。本论文系统研究了陶瓷基板材料的选择与制备、微带滤波器的设计、仿真与实物加工以及测试结果分析。首先系统介绍了用于制作滤波器的微波介电陶瓷材料的发展现状以及制作陶瓷基板微带滤波器的意义。分析设计滤波器的原理并对陶瓷基板进行遴选,最终确定了MgTiO_3系xMgO-y(Ca_(0.6)-La_(0.8/3)TiO_3)微波介质陶瓷作为基板材料。确定比例为x:y=0.85:0.15时的最优微波性能能:εr=25.0±0.5,Q×f大于50000 GHz(f=4.9 GHz),τf=0±2 ppm/oC。本论文对微带线的基本特点进行系统分析,在理论基础上分别设计了4阶发卡型带通滤波器和5阶交指型带通滤波器,并在Ansoft HFSS15中进行建模,仿真和优化。本论文还系统把微波介电陶瓷的各项参数在Ansoft HFSS15中进行仿真,研究不同数值下的参数变化,带来滤波器的插入损耗、回波损耗性能的变化情况。本论文的最后,将仿真好的滤波器进行实物加工并做测试。对实际测试结果与仿真差异做对比,并分析可能带来差异性的原因;实际测试结果:(1)四阶发夹型滤波器测试结果中心频率在4.18 GHz,比4.2 GHz偏移一点,相对带宽约为7%,带内插损为3.2 dB,上边频外阻带抑制跟仿真结果几乎一致,4.8 GHz处(|S21|)衰减大于30 dB,低频段3.6 GHz处衰减大于30 dB,带内回波损耗较大(|S11|13 dB)。(2)五阶交指型微带带通滤波器测试结果中心频率为4.2 GHz,相对带宽约为14%,带内插损为2.6 dB,上边频外阻带抑制跟仿真结果一致,3.6 GHz处|S21|值衰减大于30 dB,4.8 GHz处|S21|值衰减大于40 dB,同时带内回波损耗较大(|S11|11dB)。
[Abstract]:In the era of rapid development of communication, the use of spectrum resources is becoming more and more extensive, which also leads to the narrow remaining available space. The research of high performance filter used in RF field has become one of the hot spots at present. Commercial and military communication systems have put forward some more stringent requirements for filter performance under conventional conditions: high selectivity, low loss and miniaturization. In military communication technology, especially the microstrip filter based on ceramic substrate has been paid more and more attention because of its advantages of low insertion loss, small size and high reliability. Due to the late start of ceramic filters in China and the technical blockade adopted by foreign countries, the study of high quality ceramic microstrip filters has broad prospects. In this paper, the selection and preparation of ceramic substrate, the design of microstrip filter, the simulation and physical processing, and the analysis of test results are systematically studied. Firstly, the development status of microwave dielectric ceramic materials used to fabricate filters and the significance of fabricating ceramic substrate microstrip filters are systematically introduced. The principle of filter design is analyzed and the ceramic substrate is selected. Finally, the microwave dielectric ceramics of MgTiO_3 system xMgO-y (Ca0.6 -La0.8 / 3 TiO_3) are selected as substrate materials. When the ratio of x: y = 0.85: 0.15 is determined, the optimal microwave performance can be obtained as follows: 蔚 rn 25.0 卤0.5 Q 脳 f > 50000 GHz (fr 4.9 GHz), 蟿 fN 0 卤2 ppm 路oc). In this paper, the basic characteristics of the microstrip line are systematically analyzed. On the basis of the theory, the fourth order bandpass filter and the fifth order cross-finger band-pass filter are designed, and the modeling, simulation and optimization are carried out in Ansoft HFSS15. In this paper, the parameters of microwave dielectric ceramics are simulated in Ansoft HFSS15, and the variation of parameters under different values is studied, which results in the insertion loss of filter and the change of the performance of echo loss. At the end of this paper, the simulated filter is processed and tested. The actual test results are compared with the simulation results, and the possible reasons for the differences are analyzed. (1) the center frequency of the test results of the fourth-order hairpin filter is 4.18 GHz, which is slightly offset to 4.2 GHz. The relative bandwidth is about 7, the band insertion loss is 3.2 dB, the upper side frequency external stopband suppression is almost in agreement with the simulation results, the attenuation at 4.8 GHz is greater than 30 dB, the attenuation at 3.6 GHz in low frequency band is more than 30 dB, and the intra-band echo loss is larger than 5 order cross finger microstrip with high in-band echo loss (G11 13 dB). (2). The center frequency of the bandpass filter is 4.2 GHz, the relative bandwidth is about 14, the band insertion loss is 2.6 dB, the attenuation of S21 value is greater than 30 dB, 4.8 GHz, and the attenuation of S21 value is more than 40 dB at 3. 6 GHz.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN713

【参考文献】