Study And Applications Of Generalized Electromagnetic Resonance And Electromagnetic Bandgap (EBG) Local Resonance

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.