The metallic parts of an electrical machine greatly impact the transmission of electromagnetic waves between a shaft sensor and an external receiver. A Rotor Temperature Monitoring System (RTMS) aims to enhance power transfer in open space without considering the influence of electrical machine body into account. Therefore, in this paper, an evaluation of the electrical machine bodies effect on shaft sensor transmission and propagation is realized. These effects is related to receiver antenna packaging requirements. A comparative study between two antennas is presented in this article to see which one gives a larger propagation factor using HFSS.