The production of energy by alternative environmentally friendly means that are not dependent on rechargeable pollutant batteries and regular maintenance is proposed as a promising way of powering autonomous low-consumption electronic systems. This paper presents a laboratory practice using a radio frequency (RF) energy harvesting circuit. Students learn to design and characterize a basic patch antenna, understand the process of tuning RF signals, and check operation of the system. It also considers several possible extensions and modifications that helped students enrich their knowledge of potential RF energy harvesting applications. Finally, the paper describes the feedback received from students after implementation of this laboratory practice in three academic years.