LAUSR

This letter describes a radio propagation model for a mixed environment formed by rainforest and river in Brazil's Amazon region. The model uses geometrical optics and the uniform theory of diffraction for the calculation of the electric field at the receiver, accounting for the different transmitted, reflected, and diffracted components in each of the environments. Simulation results are compared with measurements performed in Belém (Pará) at 521 MHz, showing a good fit, with an average root-mean-square error (RMSE) over all measured paths of 3.3 dB and a maximum one of 4.2 dB. The proposed model performs much better than the ITU-R P. 1546 and the Okumura Hata ones, where the comparison with measurements leads to an RMSE higher than 8 dB. In addition, by using genetic algorithms, the electrical parameters for the dense forest are obtained, enabling to slightly decrease (0.14 dB on the average of all measured paths) the RMSE of the proposed model.