基于分布式放大器和CRLH传输线的有源漏波天线设计

发布时间：2018-09-03 13:04

【摘要】：随着无线通信系统的发展,有源集成天线因其体积小,功能强,效率高等优点被广泛应用于军事和商业领域,如相控阵,功率合成,移动通信和无线传感器等方面。同时作为新兴智能天线的微带漏波天线因波束电控频率扫描特性和低剖面、易集成等优点,成为近年来的研究热点。复合左右手(CRLH)漏波天线是CRLH传输线的众多应用之一。复合左右手传输线可以同时传输快波和慢波两种模式。工作在快波区域的复合左右手传输线称为漏波天线,可实现前向后向及边向的辐射,同时又具有很低的剖面。这些优点使CRLH漏波天线可与有源器件集成或做成共形表面应用于无线通信系统。分布式放大器(Distributed Amplifier,DA)也称为行波放大器,将多个放大器沿传输线并联在一起作,在极宽的频段内实现较平坦的增益和较好的阻抗匹配。本文以分布式放大器结构和CRLH漏波天线理论为基础,利用二者的行波共性,采用电磁仿真结合试验实测的方法,对基于分布式放大器和CRLH的微带漏波天线进行研究,提出并设计了性能改进的有源集成漏波天线。本论文的主要工作如下:1.设计了一款工作在1.9GHz的小型化平衡式低噪声。利用MWO软件对3dB正交耦合器进行小型化仿真设计,使用中间加载开路枝节和阶跃阻抗线的方法有效减小了耦合臂长度,同时尽量增加带宽。小型宽带化的3dB正交耦合器较传统正交耦合器面积减小约80%。有效地缩小了电路尺寸。实测结果显示该电路性能良好,满足设计指标。2.介绍了分布式放大器的主要性能参数和工作原理。基于MEFET的小信号模型,设计了一款工作于2.5~6GHz的超宽带放大器。工作频段内,该放大器增益为10dB左右,11S小于-10dB。实测结果与仿真吻合良好。3.从复合左右手等效电路研究入手,介绍了CRLH传输线的基本分析方法和设计思路。对对称和非对称结构的CRLH漏波天线进行了分析与对比。在此基础上,分别研究并设计了工作在平衡状态下的六单元对称和非对称结构CRLH微带漏波天线。非对称结构CRLH漏波天线在工作频段2.4~6.8GHz内11S均小于-10dB,辐射波束可实现从后向向前向无缝隙连续扫描,波束扫描范围可达到-30°~50°。对称结构漏波天线工作频段为2.6~6GHz。仿真可得该天线在工作频段内11S小于-10dB,扫描范围为-60°~80°。4.利用CRLH漏波天线和分布式放大器的行波共性,将设计好的对称结构CRLH漏波天线替代分布式放大器的漏极传输线。同时设计了与漏波天线色散关系一致的集总CRLH传输线,替代栅极传输线,解决了栅极传输线与漏极传输线相位一致性的问题。实测天线各个频点的增益比较平坦,所测频点最高和最低增益差不超过2.2dB。由于分布式放大器的嵌入,该漏波天线在仅6个单元的较小尺寸下实际增益达到5.5dB左右,显著增加了有效辐射面积。
[Abstract]:With the development of wireless communication system, active integrated antenna is widely used in military and commercial fields, such as phased array, power synthesis, mobile communication and wireless sensor, because of its small size, strong function and high efficiency. At the same time, microstrip leaky wave antenna, as a new smart antenna, has become a research hotspot in recent years because of its advantages such as beam electronic frequency scanning characteristics, low profile, easy integration and so on. Compound left and right hand (CRLH) leaky wave antenna is one of the many applications of CRLH transmission line. The composite left-right-hand transmission line can transmit both fast and slow waves at the same time. The compound left-right hand transmission line working in the fast wave region is called the leaky wave antenna which can realize the forward backward and side radiation and at the same time has a very low profile. These advantages enable the CRLH leaky antenna to be integrated with active devices or made into conformal surfaces for use in wireless communication systems. Distributed amplifiers (Distributed Amplifier,DA), also called traveling wave amplifiers, are parallel along transmission lines to achieve flatter gain and better impedance matching in very wide frequency bands. Based on the structure of distributed amplifier and the theory of CRLH leaky wave antenna, the microstrip leaky wave antenna based on distributed amplifier and CRLH is studied in this paper by using electromagnetic simulation combined with experimental method. An improved active integrated leaky antenna is proposed and designed. The main work of this thesis is as follows: 1. A miniaturized balanced low noise working in 1.9GHz is designed. The miniaturization simulation design of 3dB orthogonal coupler is carried out by using MWO software. The open branch and step impedance line are used to reduce the length of the coupling arm and to increase the bandwidth as much as possible. Compared with the traditional 3dB coupler, the area of the small broadband 3dB coupler is reduced by about 80%. The circuit size is reduced effectively. The measured results show that the circuit has good performance and meets the design index. 2. 2. The main performance parameters and working principle of distributed amplifier are introduced. Based on the small signal model of MEFET, an ultra wideband amplifier working in 2.5~6GHz is designed. In the operating frequency band, the gain of the amplifier is about 11s of 10dB and less than -10 dB. The measured results are in good agreement with the simulation. The basic analysis method and design idea of CRLH transmission line are introduced from the research of compound left-hand equivalent circuit. The CRLH leaky wave antennas with symmetric and asymmetric structures are analyzed and compared. On this basis, the six-element symmetric and asymmetric CRLH microstrip leaky wave antennas working in equilibrium state are studied and designed respectively. The CRLH leaky wave antenna with asymmetric structure is less than -10dB in the operating frequency band 2.4~6.8GHz. The radiation beam can be scanned continuously from backward to forward without gap, and the scanning range of the beam can reach -30 掳~ 50 掳. The operating frequency range of symmetrical leaky wave antenna is 2.6 GHz. The simulation results show that the antenna is less than -10dB in the operating frequency band, and the scanning range is -60 掳/ 80 掳路4. Based on the common characteristics of CRLH leaky wave antenna and distributed amplifier, the symmetrical CRLH leaky wave antenna is designed to replace the drain transmission line of distributed amplifier. At the same time, the lumped CRLH transmission line, which is consistent with the dispersion relation of the leaky antenna, is designed to replace the grid transmission line, and the phase consistency between the grid transmission line and the drain transmission line is solved. The gain of the measured antenna is flat and the maximum and minimum gain difference of the measured frequency is less than 2.2 dB. Due to the embedding of the distributed amplifier, the actual gain of the leaky antenna is about 5.5dB under the smaller size of only 6 units, which increases the effective radiation area significantly.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN820

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