Rigorous modal-expansion analysis of asymmetrical dipole antennas

This paper describes a rigorous analysis of asymmetrical cylindrical dipole antennas by the modal-expansion method. The analysis is facilitated by introducing two parallel plates coated with anisotropic perfectly matched layers (PML) to enclose the dipole antenna. Field expressions for all the subregions of the resulting structure can be readily derived and the expansion coefficients are found by enforcing the continuity conditions of tangential field components across the regional interfaces. Comparison with experimental data shows an excellent agreement. Numerical results are presented for the input impedances, current distributions, and radiation patterns of various dipole antennas