标题: | 应用模耦合逼近法设计被动/主动式微带线泄漏模阵列天线 Design of the Passive/Active Microstrip Leaky-Mode Antenna Array Employing Coupled-Mode approach |
作者: | 胡正南 Cheng-Nan Hu 庄晴光 Ching-Kuang C. Tzuang 电信工程研究所 |
关键字: | 泄漏模天线;微带线;leaky-wave antenna;microstrip line |
公开日期: | 1999 |
摘要: | 本论文包含两部分;内含(1)微带线阵列泄漏模之模耦合物理特性研究与探讨以及,(2)应用模耦合逼近法分析及设计被动式/主动式微带线泄漏模阵列天线之实例介绍。 论文第一部份,详列模耦合逼近法导式,以表述如何将传统复数传播常数全波计算法之非标准式特征值问题,转换成标准式特征值问题,使吾人可同时计算获得,存在于微带线阵列之特征值(耦合泄漏模),以及特征向量(耦合泄漏模电流分布),而不论微带线数目之多寡,因此计算时间及容量均可大幅减少。再经由繁复推导导式,微带线数目为二、三、四阵列中之电磁耦合系数可计算得之。理论数据证实,微带线阵列中,电磁耦合系数之振幅,会随微带线间之距离增加而递减。最后由一组共分馈送(corporate-fed)网路,及八条微带线组成之阵列天线实例计算验证,更进一步发现此构型阵列天线有八耦合泄漏模,其中仅四耦合泄漏模被激发,并经由测量的天线场形数据,验证文中所提理论分析摸式之正确性。 第二部分提出两种应用实例,其一为全新型紧密并排相邻之微带线泄漏模阵列天线设计,经由实例验证,适当操作四个被激发耦合泄漏模结果,高效率微带线泄漏模阵列天线得以达成。数值分析数据,显现衰减常数略为增加,然相位常数几乎维持不变,此结果会导致背后波束降低、效率提升,而不致于影响设计之波束指向。另一设计实例,展现一种新奇的注入锁定主动积体微带线泄漏模阵列天线设计方式,应用准光学空间功率合成技术,达成波束扫瞄。由前述电磁耦合系数理论值,再利用凡德波(Van Der Pol)方程式可精确摸拟非线性特性,进而掌握主动积体微带线泄漏模阵列天线重要物理参数诸如波束指向、天线场形之分析。最后两种设计实例,经由实验验证,其测量到数据和理论值相当吻合。 This thesis consists of two parts, including 1) investigation of the mode coupling of the complex-wave inhering in the microstrips array , and 2) analysis and design of the passive/active microstrip leaky-mode antenna array employing coupled-mode approach. The first part presents the coupled-mode approach to the analysis and design of large leaky-mode array, in which an N-element microstrip array supports N coupled leaky-modes at first higher order (leaky EH1 modes). The second part proposes a novel design of a closely coupled microstrip leaky-mode antenna array and an injection-locked coupled microstrip leaky-mode antenna array. In the first part of the dissertation, following a brief description of conventional, full-wave, non-standard eigenvalue problem for solving the complex propagation constants, we present the detailed formulation of the coupled-mode approach, clearly showing the transformation of the nonstandard eigenvalue problem into a standard one. Thus all the eigenvalues (complex propagation constants) and the eigenvectors (modal current distributions) are solved simultaneously, regardless of the size of the array (N). Closed-form expressions for obtaining the coupling coefficients of orders two, three, and four are presented. Theoretical studies of closely coupled microstrip arrays of two, three, and four elements show that the magnitude of the coupling coefficient Ci,i+j between element i and element i+j decreases at the order of 10-j. Finally, an example of applying the proposed coupled-mode approach for analyzing a corporate-fed, leaky-mode array of eight elements is reported, revealing that only four out of the eight leaky modes are excited. The coupled mode theory predicts the far-field radiation pattern in the main beam region in excellent agreement with the measured results. In the second part of the dissertation, two design examples are proposed. The first design example presents a novel design for a closely coupled microstrip leaky-mode antenna array. It demonstrates that high-efficiency printed array is achieved by employing closely coupled microstrip leaky-mode antenna array operating in four excited coupled EH1 modes. Numerical results of this study indicate that the attenuation constant □/ko is increasing –while the propagation constant □/ko is almost unchanged due to mode coupling between leaky lines. This phenomenon, in turn, reduces the backlobe and enhances radiation efficiency while maintaining the beam pointing direction in the desired direction. The second design example proposes a new design for beam scanning array based on the concept of quasi-optical power combining using the microstrip leaky-mode antenna array. It demonstrates that the coupling parameters can be obtained numerically, leading the analysis of the steady-state phase relationships of the coupled oscillators based on ven der pol equations for determining the excitation signals of the array. Finally prototypes of the proof-of-concept design examples are built for experimental validation, demonstrating excellent correlation between the measured results and theoretical predictions. |
URI: | http://140.113.39.130/cdrfb3/record/nctu/#NT880435099 http://hdl.handle.net/11536/65939 |
显示于类别: | Thesis |