In this work the study of the electric field propagation is presented for two typical mixed paths in the Amazon region. A first scenario discussed is Belém-Bay Guajará located in the state of Pará. This path has 24% of land and 76% of water. A measurement campaign was carried out over land and over water; using the digital channel 22 of a TV station in the frequency of 521 MHz. Were measured a total of 239 points, including 19 over ground and 220 over water distributed in 3 Radials. Data were compared with various empirical and deterministic propagation models, found in the literature. The metric to test the performance of the models was the RMS error. Furthermore, it is proposed in this paper, the combination of two models: ITU-R P.1546 and Millington. This model had the lowest RMS error compared to the other models used in this work and follows the signal behavior in the transition area land-water, where the signal experiences an increment of the electric field strength, a phenomenon known as "Recovery Effect." Other models used were: Okumura-Hata, Free space, Dyadic Green's function, ITU-R P.1546-5 and Ray Tracing. Such models did not adapt to the signal behavior. In order to evaluate the proposed model a second scenario was used Belém-Mosqueiro, this has 25% of water and 75% of land. In this case, the data was measured only over land, the water data were obtained by simulation. In this situation, the data calculated with the proposed model has agreement with measured data. The simulated water data showed the characteristic of "Recovery Effect," phenomenon that is not described by the other models. It is concluded that the combination of the ITU-R P 1546-5 and Millington models has a better agreement with the data measured on mixed paths land-water than the other models.
|
