Calculation of Fields Radiated from Conical Horn by Using Mode-Matching Method

The eigenfunctions of spherical coordinates are used to define the fields which exist inside and outside the horn aperture respectively.The mode matching technique is used for analysing the transitions from horn antanna to free space.The discontinuities caused by the transitions from horn to free space are taken into account.The scattering matrices are used to describe the mode coupling at the transitions,and the numerical convergence is considered as well.