Department of Biosystems Engineering, Faculty of Agricultural Sciences, Aarhus University, Blichers Alle 20, P.O. Box 50, Tjele DK-8830, Denmark.
Sensors (Basel). 2011;11(9):8295-308. doi: 10.3390/s110908295. Epub 2011 Aug 25.
Wireless sensor networks (WSN) have been studied in a variety of scenarios over recent years, but work has almost exclusively been done using air as the transmission media. In this article some of the challenges of deploying a WSN in a heterogeneous biomass, in this case silage, is handled. The dielectric constant of silage is measured using an open-ended coaxial probe. Results were successfully obtained in the frequency range from 400 MHz to 4 GHz, but large variations suggested that a larger probe should be used for more stable results. Furthermore, the detuning of helix and loop antennas and the transmission loss of the two types of antennas embedded in silage was measured. It was found that the loop antenna suffered less from detuning but was worse when transmitting. Lastly, it is suggested that taking the dielectric properties of silage into account during hardware development could result in much better achievable communication range.
近年来，无线传感器网络（WSN）已经在各种场景中进行了研究，但几乎所有工作都是使用空气作为传输介质完成的。本文针对在异质生物质（本例为青贮料）中部署 WSN 所面临的一些挑战进行了探讨。使用开口同轴探头测量了青贮料的介电常数。在 400MHz 至 4GHz 的频率范围内成功获得了结果，但较大的变化表明，应该使用更大的探头以获得更稳定的结果。此外，还测量了螺旋天线和环形天线的失谐以及嵌入青贮料中的两种天线的传输损耗。结果表明，环形天线受失谐的影响较小，但在传输时性能较差。最后，建议在硬件开发过程中考虑青贮料的介电特性，可以实现更好的通信范围。
