A Dual-Frequency Ultralow-Power Efficient 0.5-g Rectenna

The second annual Student Wireless Energy Harvesting (WEH) Design Competition was held during the 2013 IEEE Microwave Theory and Techniques Society (MTT_S) International Microwave Symposium (IMS2013) in Seattle, Washington, United States. This year, the competition parameters were modified from those of last year [1], and a new figure of merit (FoM) was established. The overall goal of the competition was to demonstrate low-mass hardware that can efficiently receive and rectify extremely low-incident power densities at two frequencies, with a fixed dc load. As the radio-frequency (RF) environment gets more saturated with spurious power, designs from this competition will become a feasible way to energize ultralow-powered or low-duty-cycle hard-to-reach sensors. Concepts such as Internet-of-Things, in which small ubiquitous devices and sensors will log data and send it to the cloud, could benefit from wireless energy harvesters. These sensors will not have convenient ways to stay powered unless power harvesting circuits are used for the sensor hardware.