A Simple Polarization-Diversity Demodulation System Design for Simultaneous Wireless Power and Information Transfer

Conventional simultaneous wireless information and power transfer methods demodulate the received signal at RF frequency. This part of the RF power can no longer be rectified, which causes a power transfer efficiency deterioration. To overcome this problem, a simple systematic configuration is proposed in this article. The system consists of TX and RX parts. By mapping the communication symbol “1” and “0” into two orthogonal polarizations of the TX antenna, the information can be modulated through the switching between polarization. At RX side, a dual-polarized RX antenna delivers the power to a dual-branch rectifier. By sampling and comparing the output DC voltage of the two branches, the signal can be demodulated, and the power conversion efficiency (PCE) can be maintained high owing to the ultralow-power composition of the sampling components. In the measurement, 64.7% optimal PCE is found at 7 dBm, and a degradation of less than 1% in efficiency is found when receiving the modulated signal with 9600 bps baud rate. With a simple comparator, data rate can reach 2 Mb/s with a bit error rate (BER) of$2.4^{\ast } 10^{-3}$. At the TX part, the switching loss brought by the modulation is found 0.5 dB. The whole system is concise and compact. The proposed design is a good candidate for applications that need highly efficient power transmission and reliable communication with lower data rate, such as Internet-of-Things systems.