Planar Photonic Crystal Research

In this thesis we study the method to achieve the miniaturization of planar photonic crystals,also termed electromagnetic bandgap(EBG)materials,and the electrical tuning of bandgaps.The thesis is organized as follows.In the first chapter,the origin of EBGs is discussed,together with the progress of EBG studies and applications.In the second chapter,the theoretical methods for EBG simulations are discussed, including the traditional LC resonance theory and the resonator theory,which are developed based on the antenna theory in order to facilitate the design of compact EBG materials.The third chapter presents our results on one-dimensional(1D)EBG materials. Although two-dimensional(2D)EBG are irreplaceable because of good performance such as isotropy,1D EBG materials show some better features than 2D ones in some specific applications such as the miniaturization potential and bandwidth in microstrip systems.We also find that 1D EBG materials can depress the mutual coupling in multi-antenna systems like 2D systems.The fourth chapter shows our design of electrically tunable 1D EBG materials. Over 2D structures,our fabricated tunable 1D EBG materials can considerably lower the cost since 1D structures possesses much less cell numbers.The distinct difference between our design and the most published works is that the EBG cells of our design are placed on the ground plane.As a result,our tunable EBG structures can be used as tunable band-stop filters or phase shifters by using the slow wave effects at the band edge.Conclusions are given in the final chapter.