Vegetation Effect in Paddy Field for a Wireless Sensor Network

In this paper, we report the influence of vegetation in paddy fields with antenna height as a parameter for 2.4GHz (3mW) and 920MHz (20mW) propagation. From the viewpoint of practicality, a commercially available wireless communication module equipped with a small pattern antenna was used for the experimental apparatus. In order to consider the worst case of communication loss, detailed measurements were made assuming the height of rice grown 105 cm, and the antenna height was 55cm, 105cm, 155cm. Based on the measurement results, fitting was performed on the Exponential Decay (EXD) model, and the propagation characteristics in paddy fields were verified. As a result, at 2.4GHz, even under line-of-sight conditions, there was attenuation due to the influence of scattering of reflected waves due to plant arrangement, and it was found that the same degree of remarkable attenuation due to vegetation occurred regardless of the height under rice top. On the other hand, at 920MHz, which is said to have strong diffraction, it was revealed that the loss characteristic of vegetation is proportional to the height.