ABSTRACT
This chapter presents a design methodology for the synthesis of multiband and broadband electromagnetic bandgap devices based on the mushroom or Sievenpiper structure. It investigates the theoretical basis behind the non-uniform capacitive loading of electromagnetic bandgap (EBG) surfaces and presents the theoretical analysis of the proposed methodology. A mushroom- type metasurface behaves like a narrowband artificial magnetic conductor (AMC). The mushroom unit cell is one realization of what is usually referred to as a composite right-/left-handed (CRLH) transmission line. The chapter presents a compact methodology that allows wideband or multiband surface wave suppression through capacitive loading of a mushroom-type EBG. Without a circuit representation of the EBG, the effects of a certain capacitor loading could only be examined through computationally demanding 3D full- wave simulations. The absorption bandwidth that can be achieved using the mushroom-type unit cell is rather limited. This is primarily due to the reduced capacitance tunability that the patch- type frequency-selective surfaces (FSS) offers.
