This work proposes the design of a Wireless Power Transfer (WPT) system in the 2.4 GHz band, suitable for remotely energizing low-power wireless sensors located in highly complex environments from the electromagnetic propagation point of view. This is the case of many industrial scenarios such as industrial machineries or automotive engines, to enable remote monitoring, predictive maintenance and components diagnosis. A co-designing method was used to obtain a system of independent RF sources embedded in the complex environment, with the aim of being at the same time miniaturized for easy integration into the environment, and of having the ability for providing energy wirelessly in a pervasive way. The validation of the project shows that even wireless sensors located in critical and NLOS (Non-line-of-sight) positions, placed in key points of the engine compartment and in contact with parts that need to be monitored, can be successfully energized by the proposed approach. This enables battery-less sensors to be powered and to simultaneously communicate with a gateway in order to monitor vital engine parameters. A communication among the gateway and a number of battery-less sensor nodes is demonstrated exploiting low-power LoRa (Long Range) nodes working in the same frequency band of the RF powering system.