Electromagnetic fields of a thin circula loop antenna above a (un)grounded multi-layered chiral slabs: The non-uniform current excitation

Abstract

The technique of dyadic Green's function (DGF) expressed in terms of the normalised cylindrical vector wave functions is adopted in this study for examining the electromagnetic fields excited by one thin circular loop antenna above a (un)grounded multi-layered chiral slabs. The current carried on such a circular loop antenna is expressed in a generalized Fourier series so as to incorporate practical situations. Thereby, exact representations of the radiated fields in both near and far zones are obtained in closed form, in a superposition of the right-and left-handed circularly polarized waves. Furthermore, numerical results are presented to show the radiation characteristics of the loop antenna in different layered chiral slab structures. The contributions of the lower- as well as higher-order current excitations to the far-zone field are examined in detail.