Rotman Lens is one of the most important millimeter wave devices. The Rotman Lens here includes 16 input ports and 39 output ports. The inside wall is coated with absorbing material. The geometry dimensions in the horizontal directions are 70 and 40 wavelengths, respectively. The computational domain is discretized into 1900x1600x40 non-uniform cells. It took 4 hours for GEMS Box to simulate it for 20000 time steps.