DRA Analysis using Simple and Flexible FDTD Subgridding Scheme

Various electromagnetic computational problems can be solved effectively by the finite-difference time-domain (FDTD) method. When structures contain sharp discontinuities or electrically small objects, the FDTD computational region needs to be discretized with fine mesh. If the mesh size is reduced throughout the FDTD computational domain to deal with such a situation, extensive computational resources, such as memory and time, are required. To overcome this problem, the subgridding method for local mesh refinement was proposed to increase the accuracy without increasing the numerical cost significantly. In this paper, interpolation between both electric and magnetic fields around the interface of the main grid (MG) and the local grid (LG) is used to approximate the MG-LG interface fields in the proposed subgridding scheme. As an example, dielectric resonator antennas (DRAs) operating in waveguide or free space are studied here by using the proposed subgridding scheme, which enables to tune DRA and the feeding probe dimensions in order to obtain better matching and radiation characteristics. Performance of the 3-D algorithm is validated numerically