1. Institute of Terrestrial Ecosystems (ITES), Swiss Federal Institute of Technology (ETH); CHN E29, Universitätstr. 16 CH-8092 Zürich Switzerland
2. USDA-ARS; Great Plains Systems Research Unit; Fort Collins CO USA
3. Institute of Applied Physics, University of Bern; Sidlerstrasse 5 CH-3012 Bern Switzerland
4. Laboratory for Electromagnetic Fields and Microwave Electronics; ETHZ; ETZ K 88, Gloriastrasse 35 CH-8092 Zürich Switzerland
5. Institute of Terrestrial Ecosystems (ITES), Swiss Federal Institute of Technology (ETH); CHN F 28.1, Universitätstr. 16 CH-8092 Zürich Switzerland