In this paper, a realization to synthesize the recently invented concept of a D'B' boundary is studied numerically. The idea behind the realization is to cover a DB boundary by a quarter-wave transformer with strongly uniaxial permittivity and permeability dyadics. In the numerical computations, the extreme parameters are approximated by finite values and the deviation of the behavior of the structure from that of an ideal D'B' boundary is evaluated. It turns out that when the axial constitutive parameters are large but not infinite, the performance degrades for grazing-incidence waves. On the other hand, when the DB boundary below the transforming layer is approximated by a material half space with very-low refractive index, the performance of the D'B' response suffers for wave spectrum close to the normal incidence.