A Self-Matched Multi-Band Rectifier for Efficient Electromagnetic Energy Harvesting

With the rapid development of wireless technologies, the electromagnetic energy scattered in the environment becomes one of the most attractive energy sources for low power devices which are highly demanded in various applications. Since the available electromagnetic signals may have different frequencies, the corresponding receiving antenna and rectifier are required to support multi-band operation to obtain as much energy as possible. However, existing multi-band rectifiers usually have a complex structure or unsatisfactory performance. For this issue, a self-matched rectifying structure is proposed. The theoretical analysis of the proposed configuration demonstrates the unique self-matched characteristics, which is important to implement multi-band operation with simplicity in design procedure and structure. For validation, two rectifiers are designed, fabricated and measured. The dual-band rectifier achieves measured conversion efficiencies of 69.37% and 55.28% at 2.38 GHz and 4.99 GHz with 5 dBm input power in actual measurement, respectively. Owing to the self-matched property, a tri-band design operating at 1.78 GHz, 2.35 GHz, and 4.97 GHz can be easily implemented and achieve efficiency of 60.95%, 71.37%, and 54.01% under test, respectively. Compared with the existing works, the proposed rectifier has high simplicity in both design and structure maintaining high conversion efficiencies at different frequencies.