In this study a numerical design of a new noninvasive hyperthermia applicator system capable of effectively heating deep seated brain tumor using inexpensive, simple, and easy to fabricate components. The proposed system is composed of a microstrip antenna, an ellipsoidal reflector and a head model. The irradiating antenna is placed at one of the foci of the ellipsoidal reflector while the brain tumor is placed at the other focus. The FDTD method was used to compute both the SAR patterns and the temperature distribution in a realistic 3D head model from MRI-derived data with seventeen different tissue structures. Several improvement steps were performed on all of the applicator system configurations to adequately ensure sufficient and focused energy deposition and temperature distribution in brain tumors.The obtained results show the feasibility of designing a noninvasive brain hyperthermia treatment system capable of raising the temperature of tumors within the brain to sufficient therapeutic values using simple inexpensive components.