Designs and optimizations of EBG structures

Abstract

After demonstrating some interesting characteristics of EBG structures, this chapter focuses on how to achieve these characteristics by properly designing the EBG structures. A parametric study on the mushroom-like EBG structure will be presented first. Then two popularly used planar EBG structures, mushroom-like EBG surface and uni-planar EBG surface, are compared with each other to develop some selection guidelines for potential applications. Novel EBG designs such as polarization-dependent EBG (PDEBG), compact spiral EBG, and stack EBG structures will also be studied. Furthermore, the particle swarm optimization (PSO) technique is implemented to design EBG surfaces. At the end of this chapter, some recent research trends are summarized, including space filling curve EBG surfaces, multi-band EBG designs and reconfigurable EBG structures. Parametric study of a mushroom-like EBG structure Electromagnetic properties of an EBG structure are determined by its physical dimensions. For a mushroom-like EBG structure shown in Fig. 4.1, there are four main parameters affecting its performance [1], namely, patch width W , gap width g , substrate thickness h , and substrate permittivity e r . In this section, the effects of these parameters are investigated one by one in order to obtain some engineering guidelines for EBG surface designs. Note that the vias' radius r has a trivial effect because it is very thin compared to the operating wavelength. In this study, the FDTD/PBC technique [2–3] is used to characterize the reflection phase of the EBG structure. Normal incidence is considered here.