Stability, accuracy and application of an FDTD-TDFEM algorithm [patch antenna example]

Hybrid methods can offer significant advantages for geometries where different regions of space have different characteristics. Here we describe a hybrid scheme which combines FDTD and TDFEM. An application that clearly shows the advantages of the hybrid is the calculation of the radiation diagram of a 1 GHz patch antenna, mounted on the rear-view mirror in a car. For good accuracy, the patch must be resolved with a rather fine grid, but it would be very costly in terms of memory and execution time to use such a grid for the entire car. The hybrid allows high resolution around the antenna, while the rest of the car can be resolved with standard resolution.