SEM-based analysis of antenna radiation properties

A novel analytical singularity-expansion-method-based approach to the modeling of transient antenna radiation is presented. Any electromagnetic field prediction model can be used to derive a minimal spherical harmonic expansion of the equivalent currents excited along a Huygens surface enclosing the antenna under analysis. In this way, the time-domain electromagnetic field radiated in the Fraunhofer region is evaluated analytically in terms of a newly introduced class of incomplete modified Bessel functions as the superposition of non-uniform spherical wave contributions which account for the natural resonant processes occurring in the structure.