ZigBee wireless communication is used for data transmission between two entities. The power consumption of the unit might fall below a few mW. This energy can be provided by using the RF energy harvesting to wirelessly charge a supercapacitor mounted along with the device architecture. The proposed research work offers a significant solution for the battery replacement and tedious work of the circuit maintenance. A rectenna operating at 920 MHz frequency band is used to charge the supercapacitor with high energy levels that can reach up to a few orders of mW. The harvested energy is rectified by a voltage doubler rectifier configuration. The circuit performance is evaluated, tested, and validated to show the agreement between simulation and measurement data. The system shows that the rectenna can provide at least 3 V for the sustainable operation of the ZigBee module. The connection is programmed to initialize every 5-10 seconds so the supercapacitor can re-charge back to the full capacity. The circuit is experimentally tested for continuous operation in a real environment for more than 24 hours.