Electromagnetic properties of regular arrays of nonreciprocal inclusions are analytically studied. We consider periodical planar arrays and determine the induced dipole moments in the particles taking into account the field interactions between inclusions. The emphasis is on the energy balance and polarization transformation in the arrays excited by plane normally incident electromagnetic waves. In this case, the scattering from individual inclusions does not lead to any power loss, since only plane waves are reflected and transmitted. We show how this phenomenon is described in terms of the interaction field, and analytically calculate the reflection and transmission coefficients. As an example, polarization transformation properties of arrays of small ferrite spheres are studied and compared with the properties of solid ferrite slabs.