Antipodal Vivaldi antennas dedicated to in-situ broadband microwave permittivity measurements

In the context of the ESA's SMOS and the ESA's BIOMASS space mission, the data processing algorithms require precise permittivity models of the different wood species. To develop the models, in situ sensors that could be easily deployed on the site dedicated to calibration/validation studies would be truly relevant. Microwave volume analysis can be a very useful tool to monitor material properties. There are very few commercial equipment dedicated to in-situ measurements and none of them is developed in order to leave the instrument on site for automatic measurements with specific constraints such as communication, low power consumption, frequency broadband, non-invasive measurement and cheap price. The main objective of the study presented is to develop an equipment to meet these challenges. In this article we will present the study that we conducted to design the broadband antennas needed by the device to perform efficient in situ measurements. Preliminary results on a concrete structure demonstrate the possibility to perform quality B scan despite the strict imposed specifications.