【作者】 王勇；

【导师】 崔勇；

【作者基本信息】 北京交通大学 ， 通信与信息系统， 2015， 硕士

【摘要】 背腔式缝隙天线(CBS A, Cavity-backed Slot Antenna)早在20世纪60年代就受到了极大的关注,具有坚固可靠、共面性好和易加工等优点。然而背腔式缝隙天线始终没有形成完整的设计理论,而且受当时计算机运算能力的限制,使得这类天线的实用化设计非常困难。现在随着仿真计算能力的提升,在许多共面性要求较高的领域,背腔式缝隙天线越来越受到重视。本文在理论分析、数值仿真的基础上,设计制作了室外使用的(2.4GHz和WIFI双频段)背腔式缝隙天线。本文主要在背腔深度对缝隙天线辐射性能的影响、天线输入阻抗电路模型的建立、天线的实用性以及多频点设计等方面进行了研究,主要的工作和创新成果如下：1.关于学术上背腔深度采用二分之一还是四分之一波长,是波导波长还是空气波长的争论,本文基于对波导内电磁波反射模型的分析,明确了当背腔深度等于四分之一波导波长时,背腔式缝隙天线的辐射能量最大。2.根据背腔结构对缝隙天线输入阻抗影响的仿真结果,提出了一个全新的背腔式缝隙天线输入阻抗的电路模型。3.对影响天线性能的缝隙长度、背腔深度、馈电位置和天线负载(包括防雨薄膜和电路模块)进行了仿真分析,得到了背腔式缝隙天线设计的经验性结论：背腔式缝隙天线可以通过改变缝隙长度和背腔深度来调节天线的谐振频率,通过调整馈电位置来实现天线的阻抗匹配。实测结果表明,设计的2.4GHz背腔式缝隙天线可以替代传统的单极子鞭状天线。4.采用两种方法设计了工作在WIFI频段的双频背腔式缝隙天线。第一种方法通过改变天线的缝隙长度和馈电位置来获得多频特性,其优点是加工工艺简单,天线带宽与增益特性适中；另一种方法是将背腔结构与微带缝隙天线结合,形成背腔式微带缝隙天线。针对背腔结构带来的阻抗匹配恶化的问题,本文通过在缝隙上加金属贴片和在背腔底部加十字金属带的方式改善了天线的阻抗匹配特性。实测与仿真结果显示,这两种方法设计的天线都可以工作在2.4GHz和5.2GHz频段。更多还原

【Abstract】 Cavity-backed Slot Antenna (CBSA) has been studied since1960s, which owns many advantages, such as solid, co-planarity and easy processing. However, CBSA has never formed a complete theory model, and the limit of poor operation ability of computer at that time makes it difficult for the practical design of CBSA. Now, with the improvement of the simulation ability, CBSA is paid more and more attention in some fields where coplanarity needs high quality. On the basis of theoretical analysis and numerical simulation, the2.4GHz and dual-frequency WIFI CBSA are designed, which are suitable for outdoor communication. This thesis focuses on the effect of the cavity-backed depth to the radiation characteristic of slot antenna, the building of the antenna input impedance circuit model, the practicability and dual-frequency of the CBSA. The main work and achievements are as follows:1. About the academic debate of the cavity-backed depth which should be half or one quarter, waveguide wavelength or air wavelength. This thesis clears that when the cavity-backed depth equals one quarter waveguide wavelength, the CBSA will have the maximum radiation. The conclusion is based on the analysis of the electromagnetic wave reflection model in the waveguide.2. This thesis puts forward a new input impedance circuit model of the CBSA based on the simulation results of the cavity-backed depth to the slot antenna input impedance.3. According to the simulation analysis results of the slot length, cavity-backed depth, feed place and antenna loads (rainproof membrane and PCB circuit are included) which will affect the antenna, the empirical conclusions of the CBSA design are got. The conclusions are that the antenna resonance frequency is up to the slot length and cavity-backed depth, the antenna impedance matching is up to the feed place. The test results show that the2.4GHz CBSA can completely replace the common monopole whip antenna.4. It designs dual-frequency CBSA working at WIFI band with two methods. The first method can get dual-frequency by changing the slot length and feed place. The advantage of this method is simple processing, moderate antenna bandwidth and gain. The other method combines the cavity-backed structure and microstrip antenna, forming cavity-backed microstrip slot antenna. With the problem of the impedance matching worsen by the cavity-backed, this thesis takes the methods of the metal sheet in the slot and the cross metal stripline in the cavity-backed, so that the impedance matching status can be improved. The test and simulation results show that the two kinds of antenna designed can work at2.4GHz and5.2GHz.更多还原