The article discusses the propagation of electromagnetic waves in wireless personal communications systems, focusing on the frequency range from hundreds of MHz to a few GHz. It highlights the importance of understanding propagation mechanisms, including reflection, diffraction, and scattering, for reliable communication. The authors describe the impact of these mechanisms on signal strength, fading, and interference, and introduce models for predicting path loss and multipath delay spread. The article also covers outdoor and indoor propagation environments, detailing the characteristics of macrocells and microcells, and the challenges of predicting radio coverage between floors in buildings. Additionally, it explores the use of computer-aided design (CAD) tools for indoor propagation prediction and the factors affecting RF penetration into buildings. The conclusion emphasizes the ongoing need for advanced modeling and classification methods to achieve ubiquitous wireless personal communications services.The article discusses the propagation of electromagnetic waves in wireless personal communications systems, focusing on the frequency range from hundreds of MHz to a few GHz. It highlights the importance of understanding propagation mechanisms, including reflection, diffraction, and scattering, for reliable communication. The authors describe the impact of these mechanisms on signal strength, fading, and interference, and introduce models for predicting path loss and multipath delay spread. The article also covers outdoor and indoor propagation environments, detailing the characteristics of macrocells and microcells, and the challenges of predicting radio coverage between floors in buildings. Additionally, it explores the use of computer-aided design (CAD) tools for indoor propagation prediction and the factors affecting RF penetration into buildings. The conclusion emphasizes the ongoing need for advanced modeling and classification methods to achieve ubiquitous wireless personal communications services.