Investigation of instability characteristics arising in the FDTD simulation of electrically large antenna arrays

In this paper, we investigate the instability problem that arises in the FDTD simulations of an electrically large problem. When the configuration to be simulated includes many small features such as thin slots, dielectric slabs of small thickness, thin PEC or curved objects, the problem becomes challenging in terms of memory requirement even when parallel FDTD is used in conjunction with a non-uniform mesh. Additionally, a non-uniform mesh in the PML region triggers some instabilities in the solution when a conventional PML boundary condition is used. In this paper, we propose some practical ways to overcome such instability problems, by using an antenna array to illustrate the application of the proposed techniques.