Lecture 7-Okumura and Hata Macroscopic Propagation Models

In this section Okumura and Hata propagation models are discussed. The two models or their modified version are frequently used throughout commercially available RF engineering tools. 1.1 Okumura Propagation Model Okumura's model is one of the most frequently used macroscopic propagation models. It was developed during the mid 1960's as the result of large-scale studies conducted in and around Tokyo. The model was designed for use in the frequency range 200 up to 1920 MHz and mostly in an urban propagation environment. Okumura's model assumes that the path loss between the TX and RX in the terrestrial propagation environment can be expressed as: ru tu mu FS H H A L L + + + = 50 (1) where: 50 L-Median path loss between the TX and RX expressed in dB FS L-Path loss of the free space in dB mu A-" Basic median attenuation " – additional losses due to propagation in urban environment in dB tu H-TX height gain correction factor in dB xu H-RX height gain correction factor in dB The free space loss term can be calculated analytically using: () () r t FS G G f d L log 10 log 10 MHz 1 log 20 km 1 log 20 45. 32 − −         +         + = (2) where: d-Distance between the TX and RX in km f-Operating frequency in MHz r t G G ,-TX and RX antenna gains (linear) The remaining terms on the right hand side of (1) are provided in a graphical form as the family of curves.