Impact of antenna height on propagation characteristics of 2.4 GHz wireless channel in wheat fields

It will provide the foundation for researches on wireless sensor network deployment and power control to study the wireless channel propagation characteristics in cropland environments. The power attenuation and the packet loss rate (PLR) of 2.4GHz radio signals were measured in wheat fields at different growth stages with the transmission ranges of nodes and the path loss further attained, and then the path loss model was built through regression analysis using MATLAB. The results showed that the attenuation speed of signal power monotonically decreased, and transmission range monotonically increased with the increase of antenna height, respectively. Therefore, the optimal height of antenna was about 1.2 m, which was a little bit higher than that of mature wheat plants. The signal attenuation at later growth stages of wheat was larger than that at earlier stages when the antenna height was kept unchanged. In addition, 2.4GHz wireless channel loss in wheat fields could be predicted by the logarithm distance path loss model, and the correlation coefficients between computational values and measurement values were between 0.961 and 0.996. Path loss index decreased logarithmically with the increased of antenna height, and increased with the growth of wheat plants.