Hybridization of Integrated Microwave and Mechanical Power Harvester

An integrated ambient kinetic and microwave energy scavenger is presented in connection with its strategy of two-level hybridization, namely structural and functional integration of the two dissimilar energy harvesting techniques. Specifically, they are related to two-resonator/transducer integration and simultaneous/collaborative rectification. An F-shaped radiofrequency antenna serves as the microwave energy collector and a Michael Faraday's generator mounted on a mechanical beam cut out of the printed circuit board acts as the electrical current producer. Both microwave and mechanical resonators are optimally designed and accommodated on the same substrate with a compact size comparable to that of a credit card (80 mm × 50 mm). The demonstrated hybrid power harvester has a capacity to operate properly with either microwave or mechanical excitation. When both power sources are accessible, it can provide a notable efficiency enhancement compared with the separate harvesting of two single sources. The measurements show that at a typical injecting AC power of -38 dBm, the rectified DC output power could be increased by at least 50% compared with a direct summation of DC output power through two separate modes. An efficiency enhancement of 85% can be achieved when diode's injecting power sources are -45 dBm. With a strong resilience, such a hybrid power harvester is able to potentially find its wide practical applications.