Far-Field Electromagnetic Energy for Low-Power Wearable Technology Devices

This paper investigates the idea of low-power wireless sensors for far-field charging; in particular, it addresses situations in which sensor location cannot be accurately detected and battery replacement is not an option. Low-power indirect wireless transmission is suitable for sensors with low duty cycles, a desired compact sensor size, and an expected radio-frequency energy consumption of 20– 200 W/cm2. A low-power CPU controls all of the sensor platform's components, including the transmission devices and readers. Electromagnetic radiation at the GHz frequency that the mast's antenna receives powers the platform. After receiving the electrical signal, the rectifier circuits employ an effective power management circuit to charge a storage device. Codesigning the power source circuit and RF powering circuits is necessary for optimal performance at lower received power density levels. Integrated antenna transformers are used in the 2.4 GHz business, mathematical, and medical bands as well as the 1.96 GHz commercial band in the hybrid and massive versions with power-management circuits. The results for both types of versions are shown.