FDTD optimizations of the bandwidth of the hat feed for MM-wave reflector antennas

The hat antenna is a low sidelobe reflector antenna for radio link applications in the MM-wave band. In the present paper we describe how the hat feed has been analyzed by using the computer code V2D Solver based on the FDTD method. The FDTD method has resulted in a big break through in the possibility of numerically controlling the radiation performance of the hat feed. In particular, the bandwidth has been tuned to a return loss better than 20 dB over a 10% bandwidth.