An enhancement of input impedance bandwidth of circular-disc loaded monopole antenna with horizontal and vertical parasitic strips

In this paper, a monopole antenna with a circular disc at the top and parasitics stips around antenna is analytically investigated and simulated using the mode-matching techninque and a commercially available software package, CST MW Studio based on FDTD algorithm. Mode-matching technique with boundary conditions are applied to compute the unknown modal coefficients in each region. For the usefulness of mode-matching technique to open boundary, the artificial ground plane is added away from the top-loading disc. Compared results between two methods show that the proper radius ang height of parasitic elements can reduce the peak value of input impedance at the resonant frequencies over wide bandwidth without power dissipation due to lossy material used in conventional ways.