The paper describes the crucial role of phantoms in Microwave Imaging (MWI) for medical devices. Accurate modelling of numerical scenarios is crucial in designing, testing, and developing MWI devices. Phantoms with appropriate tissue electrical properties are inevitable components of imaging scenarios. Therefore, high computing resources are required to develop such phantom, and EM simulation of such scenarios requires a more prolonged time. A defined blueprint is required to reduce the complexity of such scenarios to use them effectively for MWI purposes. In the given paper, a brief study of the three-dimension voxel model of the head is presented, where a unit cell is a cube with tissue-mimicking properties. The phantom is developed on the WIPL-D Pro EM simulation platform. Further, the voxels are grouped in the form of N x N x N, where N is the number of voxels on each axis. Homogenization techniques are implemented on the grouped voxels and result in one big cube, the main building element of the electromagnetic model. The RCS simulation is performed with plane wave excitation for different values of N, and the results are analyzed for convergence to the reference model. Also, the relative mean absolute deviation (RMA) of the whole phantom as a result of the homogenization process is presented and its convergence is compared with the convergence of the mean deviation of simulated results.