Parametric study of a unit cell with elliptical patch for periodic structures with variable number of grounding vias

Numerical investigation of the effect on the dispersion diagram of a different number of off-axis positioned grounding vias for an elliptic patch in periodic arrangement is presented. Various aspect ratios for the mushroom-like structure in microstrip technology have been considered. The position of the vias has been moved according to the variation of the geometry, guaranteeing an easy scalability. It was found that the degenerate geometry of circular shape guarantees the maximum width of the band-gap for almost all analyzed configurations. The band-gap decreases with the increase of the number of vias, which in turn corresponds to a transition from an open resonator to a closed cavity. A variation of more than 10% in the width of the bandgap has been observed.