端接复阻抗耦合器及其在RFID读写器微带天线的应用

发布时间：2018-05-27 01:01

本文选题：复阻抗 + 分支线定向耦合器　；参考：《大连海事大学》2017年硕士论文

【摘要】：分支线定向耦合器既具有功率分配又具有90°移相功能,被广泛应用于宽带圆极化天线和波束可切换天线阵的馈电网络中,是通信系统中一种重要的微波器件。通常分支线定向耦合器的研究方向主要为宽频耦合器、多频耦合器与小型化耦合器。在国家自然科学基金(基金号:61401056)的资助下,论文对端接复阻抗分支线定向耦合器及其在RFID读写器微带天线中的应用进行了研究。完成的主要工作包括以下几个方面:(1)提出了一种端接复阻抗分支线定向耦合器,并进行了实际设计验证。论文利用奇偶模分析法对端接复阻抗分支线定向耦合器的设计公式进行了推导,并且给出了最终的设计公式。该耦合器可以实现复数的端口阻抗,同时耦合器的直通端与耦合端可以实现不同的功率输出。(2)基于端接复阻抗分支线定向耦合器设计了一款单层电容耦合馈电宽带圆极化微带天线。该天线利用电容耦合馈电方式可以等效为一谐振电路的优点,通过选择复数的输入阻抗实现了对天线阻抗带宽的展宽。为了消除天线馈电点与3dB耦合器之间的匹配电路,利用端接复阻抗分支线定向耦合器的设计公式,设计一款端口阻抗与天线复数输入阻抗互为共轭的分支线定向耦合器,并且通过级联实现共轭匹配。(3)为提高天线的增益平坦度,对单层电容耦合馈电宽带圆极化微带天线进行改进,设计一款双层电容耦合馈电的宽带圆极化微带天线。该天线同样利用电容耦合馈电实现复数的输入阻抗,然后利用共轭匹配的方法来级联端接复阻抗分支线定向耦合器,实现圆极化波的辐射,并且与单层电容耦合馈电宽带圆极化天线进行对比与分析。
[Abstract]:The branch line directional coupler has both power distribution and 90 掳phase shift function. It is widely used in the feed network of wideband circularly polarized antenna and switched antenna array. It is an important microwave device in communication system. The research direction of branch line directional coupler is mainly broadband coupler, multi-frequency coupler and miniaturized coupler. Supported by the National Natural Science Foundation of China (Grant No.: 61401056), the paper studies the terminal complex impedance branch line directional coupler and its application in the microstrip antenna of RFID reader. The main work of this paper includes the following aspects: 1) A kind of directional coupler with complex impedance branch line is proposed and verified by practical design. In this paper, the design formula of terminal complex impedance branch line directional coupler is deduced by using parity mode analysis, and the final design formula is given. The coupler can achieve complex port impedance, At the same time, the coupler can realize different power output at the through end and the coupling end. Based on the terminal complex impedance branch line directional coupler, a single-layer capacitance-coupled wideband circularly polarized microstrip antenna is designed. The antenna can be equivalent to a resonant circuit by using the capacitive coupling feed mode. The bandwidth of the antenna impedance is widened by selecting the complex input impedance. In order to eliminate the matching circuit between antenna feed point and 3dB coupler, a branch line directional coupler with conjugate port impedance and complex antenna input impedance is designed by using the design formula of terminal complex impedance branch line directional coupler. In order to improve the gain flatness of the antenna, the single-layer capacitance-coupled broadband circularly polarized microstrip antenna is improved and a double-layer capacitance-coupled broadband circularly polarized microstrip antenna is designed. The antenna also uses capacitive coupling feed to realize the complex input impedance, and then uses conjugate matching method to cascade the complex impedance branch line directional coupler to realize the radiation of circularly polarized wave. And compared with single layer capacitance-coupled broadband circularly polarized antenna.
【学位授予单位】：大连海事大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN822;TN622

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