Performance assessment of short-range radio propagation in crop fields
1. Informatiou Engineering College, Capital Normal Cniversity, Beijing 100048, China; 2. Key Lab on Precision Agriculture System Integration Research, China Agricultural University Beijing 100083, China; 3. National Engineerlng Hesearch Center for Infnrmation Techno logy in Agricuhure, Beijing 100097, China
Abstract：In order to evaluate the performance of short-range radio propagation in crop fields, testing of path loss was performed to determine RSSI levels at different heights and distances in wheat seedling stage, booting stage and jointing stage. The results showed that pass loss of radio propagation over a 2.4 GHz frequency band at each height could be described by the log-distance path loss model. Average path loss indexes in three different stages were 1.96,2.13 and 2.42 respectively. In addition, two factors of crop structure, height of canopy and DFIN（diffuse non-interceptanee） were chosen to describe cropland environment, which could interfere with radio propagation. Correlationships between the two factors and path loss index were proved.
2010, Vol. 31 
