Finite antenna array is one of the challenging problems in the electromagnetic simulations since it usually has a large number of elements and fine features inside each element. A single processor either cannot or is very difficult to simulate this type of problems limited to its compute ability and memory amount. GEMS uses the CPUs and memory resource in a cluster to simulate a complete problem, and the problem size is determined by the number of processors and memory amount in the cluster. The example here is a feed of a reflector antenna constructed by 144 Vivaldi antennas. Since its feed structure and small gap between two Vivaldi elements are very small compared to the entire feed geometry, the memory requirement much exceeds 2GB installed in a regular computer. GEMS is able to use a group of computers and distributed memory to simulate this problem.

This feed structure includes 144 vivaldi antenna elements and is discretized into 897x897x360 nonuniform cells. It took 133 minutes using 4,000 processors in LOFAR BlueGene/L for 50,000 time steps.