# The Impact of an Electric Machine Body on EM Wave Propagation in RTMS
## 2 RTMS (Rotor Temperature Monitoring System) Design  
Wireless data transmission using radio signals employs electromagnetic wave propagation (EMWP). In the context of collecting parameters from rotating electric machines, the monitoring system serves as a crucial method for data transmission in rotational environments. This technology is widely used in aerospace, industry, automotive, and other sectors due to its broad bandwidth, excellent penetration, and long-range capabilities [16]. Common examples include systems for monitoring car and truck tire pressure and devices for data collection from rotating components [17]. A radio monitoring system typically consists of a rotating transmitter attached to the moving part and a stationary receiver nearby. Its primary goal is to ensure reliable and accurate wireless transmission of data and signals from rotating components to the stationary receiver, especially in dynamic environments. Various sensors, such as strain gauges, thermocouples, thermistors, pressure transducers, and accelerometers, convert physical measurements into electrical signals, which are then transmitted wirelessly without physical connections. A schematic of a standard radio monitoring system is shown in Figure 1.  
The rotor temperature monitoring system (RTMS) illustrates a paradigm shift in rotorcraft technology, seamlessly integrating advanced sensors and IoT capabilities within the framework of Industry 4.0 [18]. By harnessing the power of IoT, the RTMS transforms traditional rotor temperature monitoring into a dynamic, data-driven process where information is continuously transmitted and processed in a cloud-based infrastructure. Through sophisticated algorithms and machine learning techniques, the RTMS not only monitors temperature variations but also predicts potential anomalies and preemptively identifies maintenance needs, ushering in a new era of predictive maintenance in rotorcraft industry. Additionally, the RTMS boasts unparalleled precision and reliability, with sensors calibrated to nanoscale accuracy, ensuring the capture of even the slightest temperature fluctuations. This level of precision empowers operators with actionable insights, enabling them to optimize rotorcraft performance, extend component lifespans, and enhance overall operational safety. As rotorcraft continue to evolve in complexity and operational demands, the RTMS stands as a testament to innovation, driving the industry towards greater efficiency, reliability, and sustainability in aerial mobility. The applications of the rotor temperature monitoring system (RTMS) are vast and varied, spanning across multiple industries where rotorcraft plays a crucial role [19]. In the aviation sector, RTMS finds extensive utility in commercial and military rotorcraft, ensuring optimal performance and safety during flight operations [20]. It serves as a vital tool for monitoring rotor temperatures in helicopters, tiltrotors, and other rotary-wing aircraft, facilitating proactive maintenance and preventing catastrophic failures. Additionally, RTMS can be deployed in industries like marine transportation, where it monitors the temperature of ship propellers, contributing to the reliability and efficiency of marine  
Figure 1: Diagram illustrating the radio monitoring system for rotating components. vessels [21]. Moreover, in the context of research and development, RTMS can serve as a valuable asset for testing and validation of new rotorcraft designs, providing crucial data for performance optimization and safety enhancement [22]. With its versatility and reliability, RTMS stands as a pivotal technology in ensuring the integrity and efficiency of rotor systems across diverse applications and industries [22]. The rotating transmitter integrates crucial modules such as a power supply, signal conditioning module, sensor unit, transmitting antenna, and wireless transmission module. Typically housed in robust casing, this transmitter captures raw data from rotating components through various sensor units.