Attenuation of Radiofrequency Waves due to Vegetation in Colombia

We present in this paper the preliminary empirical model of the attenuation produced by nine vegetation types with diverse heights and climate conditions in Colombia. Measurements were performed in co and cross-polarization. Five frequency bands with the following central frequencies were considered: 150 MHz, 360 MHz, 580 MHz, 850 MHz, and 3600 MHz. As expected, a comparison between measurements and calculations with the Fitted International Telecommunication Union (FITU) attenuation model shows a strong dependence of the attenuation with the type of vegetation and its spatial distribution. FITU model shows a good agreement with measurements in coniferous forest and citrus plantation. On the other hand, the model presents more than 10 dBs of underestimation for some native species in the propagation losses for the highest measured frequency bands, while, for balsa, the model presents more than 10 dBs of overestimation. Based on these results, an adaptation of the existing attenuation model for propagation through vegetation, in special the FITU model, is proposed for Colombian conditions.