Perfect Matching Layer (PML) boundary conditions in Clarity 3D Workbench

PML is used widely as a boundary condition along with Finite Element Method (FEM) and Finite Difference Time Domain (FDTD) solvers. PML absorbs the electromagnetic fields at the boundaries of a computational domain by introducing fictitious anisotropic layers of materials that are designed to mimic an infinite medium.

PML layers can be applied to the boundaries of a radiation box and are designed to gradually absorb the electromagnetic fields as they enter the layers.

The PML boundary condition is considered more accurate than the ABC terminations, and its accuracy is less dependent on the angle of the incident waves.

PML can absorb the electromagnetic fields in all directions at a much closer termination distance typically needed by ABCs, making them highly effective at reducing reflections and minimizing numerical errors in these types of simulations.

The PML boundary conditions are the preferred choice when simulating complex radiating structures such as antennas.

The PML boundary condition in Clarity 3D Workbench provides three different quality levels: low, medium, and high, where 5, 10, and 15 layers of PML material can be defined around the radiation box, respectively.

The greater the number of layers, the better the absorption. However, increasing the number of PML layers leads to an increase in the simulation time. The default value of five layers is good to cover most of the scenarios.