【作者】 李龙；

【导师】 梁昌洪；

【作者基本信息】 西安电子科技大学 ， 电磁场与微波技术， 2005， 博士

【摘要】 谐振是本论文的主题。 电磁谐振是一种大家熟知的经典物理现象,但是,随着IT时代的到来和新材料(如光子晶体PCs和电磁带隙结构EBG等)的不断涌现,它也面临着各方面的挑战。复杂电磁环境的大量实践表明:在开放空间某个小区域(甚至是一个点),发现有类似谐振的强场峰值;而紧致型EBG结构可以用小周期薄层(a,t<<λ)得到局域谐振的带隙特性。正是从这些实际需求中,本文总结出通常很少论及的广义谐振和电磁局域谐振现象,并对其理论和应用作出深入探讨和研究。 “不同质的矛盾,只有用不同质的方法才能解决。”本文正是以这一思想为指导,深入研究了广义电磁谐振和电磁局域谐振的关键性质,并在此基础上提出了以复频率理论为基础,以路与场统一为思想,以广义系统函数H(s)为方法,找到一条可以解决广义电磁谐振和电磁局域谐振的有效途径。事实证明:广义系统函数H(s)方法不但能根据少数几个采样点及其复极点和留数特性正确地预测出广义谐振点,分辩出膺谐振,而且还能给出其它方法难以获取的超低Q谐振状态。 Mushroom-like EBG结构的深入研究,使我们领悟到利用波结构在一部分区域构成等效电感L,使磁性成主要矛盾,而另一部分区域构成等效电容C,使电特性成主要矛盾,它们之间的电磁耦合既可构成谐振,又可降低(或压制)波动性,这是它能大大减小结构尺寸的关键所在。值得指出:本文成功地利用广义系统函数H(s),分析和预测了其表面波带隙位置和范围,使H(s)成为分析广义电磁谐振和EBG局域谐振的一种统一方法。 文中提出了EBG结构的局域谐振腔体单元(LRCC)模型,深入研究了表面波带隙和平面波反射相位带隙的相关和不同,从而澄清了当前国际上一些著名学者的争论,为奠定完整的带隙理论打下了基础。 这篇论文中还做了不少实验,如带隙实验,缝隙天线阵列实验等,这些实验不仅使我们坚信了本文提出理论和方法的有效和正确性,更重要的是为新材料、新应用带来了新的生机。400单元的波导缝隙天线阵以及EBG缝隙子阵的实验结果满足了预想和设计指标。最重要的是,本文提出的波导端头裂缝EBG相控阵的分析和预测表明:由于EBG结构的加入确可提高相控阵性能,并有效地消除扫描盲区,扩展扫描范围。 本文共十一章,第一章作为序重点讨论体系结构,第十一章作出总结和展望。正因为本文是对新现象新问题的初步研究,尚存在大量问题值得进一步探索。更多还原

【Abstract】 Resonance is the theme of this dissertation.Electromagnetic resonance is a well-known and classical physical phenomenon. With the coming of IT age and the continuous advent of new materials such as photonic crystals (PCs) and electromagnetic bandgap (EBG) structures, the electromagnetic resonance is faced with various challenges. Many practices in the complex electromagnetic environments give evidence of strong-field peak like resonance to be found in a small region (even at a point) in the open space, and furthermore, the novel compact EBG materials can employ the small lattice cells and thin-bedded structures (a,t<<λ) to generate the electromagnetic bandgap local resonance. Based on the practical need to analyze these problems, the generalized resonance and electromagnetic local resonance phenomena are presented, and their theories and applications are discussed and investigated in this dissertation."Qualitatively different contradictions can only be resolved by qualitatively different methods." Under the guidance of this idea, an effective way of analyzing the generalized electromagnetic resonance and the EBG local resonance is presented, which is on the basis of the complex frequency theory, at the idea of the circuit and field unification, and in the method of the generalized system function H(s). The key properties of the generalized electromagnetic resonance and EBG electromagnetic local resonance are investigated accordingly. It is proved that the generalized system function H(s), according to a few of sampling points and its complex poles and residue characteristics, can not only accurately predict the generalized resonance frequency and distinguish pseudo-resonance, but reveal the resonance state with lower Q-value which is difficult to obtain in other ways.By the further study of the mushroom-like EBG structures, we found that, using wave structures to compose the equivalent inductance L in one part region where the magnetic performance is preponderant and compose the equivalent capacitance C in the other part region where the electric performance is preponderant, the electromagnetic coupling between them both forms resonance and suppresses the wave characterization. That is the key point why the EBG structure has the characteristics of compactness and can reduce its structure dimensions much less than the operational wavelength. It is worthwhile to point out that the generalized system function H(s) method is alsosuccessfully applied to analyzing and predicting the position and width of the surface wave bandgap of EBG structures. Therefore, H(s) becomes a uniform method for analyzing the generalized electromagnetic resonance and EBG local resonance.The locally resonant cavity cell (LRCC) model for mushroom-like EBG structures is presented to help us to gain insight to the physical mechanism of the EBG structures and the interaction with electromagnetic waves comprehensively. The relation between the surface wave suppression bandgap and the plane wave reflection phase bandgap is investigated and revealed, which clarifies the arguments among some international scholars, and provides a basis for establishing a complete bandgap theory.A number of experiments, such as EBG structure bandgap measurements and slot antenna array experiments, etc, are performed by this dissertation. These experiments convince us of the validity and accuracy of the theories and methods proposed by the dissertation, more importantly, they bring new vitality to new materials and new applications. A waveguide slot array with 400 elements and an EBG broadside slot antenna subarray have been analyzed, designed and tested, and the experimental results show that they successfully achieve the theoretical purpose and design target. Furthermore, it is revealed that the waveguide end-slot phased array integrated with compact EBG structures will improve the performance of the conventional phased array, effectively eliminate scan blindness and increase the ability of the array to scan wider angular sectors.The dissertation is classified into eleven chapters. Chapter 1 is the preface to describe the construction of the dissertation, and chapter 11 gives the summary and prospects. This dissertation is only a very fundamental research of this very new phenomena and questions, so there are still many problems for us to probe into.更多还原