In this contribution the technique of dyadic Green's function in terms of the normalized spherical vector wave functions is adopted for investigating the radiation of a thin circular loop antenna in a radially multilayered biisotropic sphere, and the current on the loop antenna is supposed to be a uniform, a sinusoidal as well as a generalized Fourier series distribution, respectively. The radiated fields in both near and far field zones for circular loop antenna of arbitrary radius are derived and expressed as a superposition of the right- and left-handed circularly polarized waves. Numerical results are presented to demonstrate the constitutive parameter effects of the two- and four-layer biisotropic spheres on the resonant characteristics of near fields as well as the radiated power and polarized state of the far fields for electrically large and small thin circular loop antennas excited by a uniform current, respectively.