Research On Novel Broadband/Dualband Three Dimensional Periodical Artificial Electromagnetic Structures

To meet the application requirements in Electromagnetic Compatibility(EMC) and military stealth technology, the research of three dimensional broadband and multi-band electromagnetic periodic structures was conducted. This research is mainly focused on the design and analysis of novel wave-transparent structures and wave absorbing structures. These proposed designs are easy to design with clear working principles and superior performance. The work in this dissertation is meaningful in research of electromagnetic periodic structure and its application in EMC, etc.The first chapter introduces the basic concepts of electromagnetic periodic structures and discusses the classification. By reviewing the development history of the wave-transparent structures and wave absorbing structures separately, the limitations of traditional designs are summarized. The most recent developments are also gathered in this chapter.The second chapter firstly presents fundamental theories of the simulation method and equivalent circuit method, and briefly describes the commercial software of CST and ADS. By giving the filter design theory and the closely related cross coupling theory, the controlling methodology of transmission zeros are obtained, which lays a solid foundation for the followed design of elliptic responses.In chapter three, the limitations of traditional planar wave-transparent structures are discussed. A novel design with broadband quasi-elliptic response is presented after an introduction of related recent development. The new structure consists of an array of apertured cavities, and is characterized with broad bandwidth, multiple resonances, and single-side rapid rolloff. Relationships between geometry dimensions and responses are fully investigated with simulations. Its working principles are discussed both in view of electromagnetic wave and equivalent circuit, and both of these two methods reach an agreement with the simulation result.Chapter four primarily illustrates the development of elliptic responses research,and the drawbacks such as slow transformation to stopband are discussed. Followed is the design of a novel structure with dual-band elliptic response. The transmission response is with a quasi-elliptic passband in lower frequency, and an elliptic passband in upper frequency. By placing transmission zeros near the passband edge, the proposed structure is proved to be with high selectivity, rapid rolloff, high attenuation in stopband and high separation between two passbands. Besides, the working principles and influence of the dimensional parameters are fully investigated with simulations and analysis. The design and working principles are summarized in the last section. From the result in this section, with proper phase and coupling control, transmission responses with multiply resonances and transmission zeros could be achieved with simple unitstructures.Chapter five concentrates on the study of ultra-thin absorbing periodic structures.Based on the comments of the classical absorbing structures, a “perfect” absorber is proposed and its absorption laws are investigated. Moreover, a dual-band absorber is designed with concepts of fractal or self-resemble. Finally, in light of the design of a novel Substrate Integrated Waveguide(SIW) FSS, a broadband absorber is proposed and simulated, which proves that placing two resonances closely is a useful to enhance the absorption bandwidth.