the effect on wireless sensor communication when deployed in biomass影响无线传感器部署在生物质时沟通.pdf

Sensors 2011, 11, 8295-8308; doi:10.3390/s110908295 OPEN ACCESS sensors ISSN 1424-8220 /journal/sensors Article The Effect on Wireless Sensor Communication When Deployed in Biomass Jakob Juul Larsen , Ole Green , Esmaeil S. Nadimi and Thomas Skjdeberg Toftegaard Department of Engineering, Aarhus University, Blichers Alle 20, P. O. Box 50, Tjele DK-8830, Denmark; E-Mail: ole.green@agrsci.dk Faculty of Engineering, Institute of Chemical Engineering, Biotechnology and Environmental Technology, University of Southern Denmark, Odense DK-5230, Denmark; E-Mail: esi@kbm.sdu.dk Department of Engineering, Aarhus University, Ny Munkegade 120, Building 1521, Aarhus C DK-8000, Denmark; E-Mail: tst@cs.au.dk Author to whom correspondence should be addressed; E-Mail: JakobJuul.Larsen@agrsci.dk; Tel.: +45-2445-0421. Received: 1 August 2011; in revised form: 22 August 2011 / Accepted: 23 August 2011 / Published: 25 August 2011 Abstract: 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 tw