The MTM-EBG as a Rigorous Multiconductor Model of the UC-EBG and Approaches for Miniaturization

A multiconductor transmission-line (MTL) model is proposed with which to model the uniplanar compact electromagnetic bandgap structure (UC-EBG). The model is based on a 2-D arrangement of metamaterial-based electromagnetic bandgap structures (MTM-EBGs), with a central node region. The branches of this structure are modeled as conductor-backed coplanar waveguide segments with integrated series capacitors, while the node region is modeled as a grid of microstrip (MS) lines with suitably augmented propagation velocities. The dispersion properties of the canonical UC-EBG unit cell are simulated in Ansys HFSS and compared with those of an equivalent simulation model based on a 2-D arrangement of weakly loaded MTM-EBGs, as well as similar data produced by the MTL equivalent-circuit model, which are all found to be in agreement. It is then shown that additional capacitive loading allows for substantial miniaturization, a regime in which even better agreement is produced between the equivalent circuit model's dispersion data and the data produced by an equivalent HFSS model. Using these data, the Bloch modes of this structure are analyzed in detail. Thus, the MTL perspective offers a recipe for producing highly miniaturized UC-EBG unit cells that may be successfully integrated into printed circuit board (PCB) systems for applications in parallel-plate noise and surface-wave (SW) mode suppression, among others.