Modeling Antenna Feeds by Electric and Magnetic Current Sheets in Conjunction with the Method of Moments

The Method of Moment (MoM) approach is often employed when regarding free space antenna problems. However there are limitations concerning modeling certain antenna feeds. Dealing with semi-infinite structures (e.g. waveguide excitation) methods like FEM or FDTD are favorable due to the use of absorbing boundary conditions (ABC) or Perfectly Matched Layers (PML). In this paper a surface current excitations in connection with a MoM approach is introduced. A horn antenna as well as a biconical antenna are investigated for a single mode and a multimode excitation. The role of the termination of the feeding structure with regard to multiple reflections is exploited. A comparison with published theoretical results and measurements is given.