In the context of the SMOS and the BIOMASS space-borne mission, the data processing algorithms require precise permittivity models of 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 very relevant. Microwave volume analysis can be a very useful tool to monitor wood 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, large frequency broadband, non-invasive measurement and low price. The main objective of the study presented is to develop an equipment to meet these challenges.In this article we will present the design of the broadband antennas used in the device to perform efficient in situ measurements. Preliminary results obtained over a concrete structure demonstrate the possibility to perform quality B scan despite strict imposed specifications.