Abstract-Radio Frequency Energy harvesting is a research topic of increasing interest, related to sustainability, which could become a promising alternative to existing energy resources. The paper will show all the activities addressed to design a wideband system to recover wideband energy from electromagnetic sources present in the environment. The main idea is to develop battery-free wireless sensors able to capture the available energy into the mentioned bandwidth. The final goal is to realize self-powered Wireless Networks based on Ultra Lower Power -ULP sensors minimizing the need of dedicated batteries. This last feature is particularly attractive in different kind of applications, ranging from military to civil cases. A first system prototype is shown and discussed. Conclusion follows.