Octa-Port Dual-Polarized Antenna/Rectenna for MIMO Simultaneous Wireless Information and Power Transfer (SWIPT)

Wireless sensor networks face a challenge with the limited battery capacity in IoT sensor nodes and low communication quality, hindering network sustainability and increasing maintenance costs. To simultaneously address these issues, a novel octa-port antenna/rectenna with dual-polarization capabilities is proposed for simultaneous wireless information and power transfer (SWIPT) operation. The four ports of the design realize a rectenna for wireless power transfer (WPT), and the other four ports are dedicated to MIMO operation for wireless information transfer (WIT). The rectenna has a gain of 7.2 dBi with a dc beamwidth of 72.2°. The rectenna achieves a good PCE of 50.92% at $1700~\Omega $ , translating to a dc power harvesting capacity of $72.47~\mu $ W at −8.46-dBm RF input power. The MIMO antennas maintain a bandwidth of 200 MHz, with $S_{11}$ less than −10 dB centered around 5.8 GHz. The mutual coupling between co-polarized antenna/rectenna ports and among the MIMO antenna ports is less than −12 and −25 dB, respectively.

I. Introduction

In 6G communication, to extend the lifespan of IoT nodes [1], researchers explored simultaneous wireless information and power transfer (SWIPT) to reduce dependence on external batteries and enable sustainable communication in applications, such as industrial IoT (IIoT), automated warehouse, remote surveillance, and so on. An SWIPT module employs several methodologies to execute wireless power transfer (WPT) and wireless information transfer (WIT) simultaneously. These methodologies are power splitting [2], [3], [4], [5], time splitting [2], frequency splitting [6], [7], [8], and dual polarization [9]. In the power-splitting approach, the received RF power is divided for WIT and WPT operations for individual use, which leads to a low signal-to-noise ratio (SNR) for WIT and low efficiency for WPT, whereas time splitting allocates time slots for WIT and WPT, which demands precise time synchronization [10]. In contrast, the dual-polarization and frequency-splitting schemes utilize two different polarizations and frequencies for WIT and WPT. The latter methodologies are less complicated than others, as they do not require any extra circuitry, such as a power splitter or time synchronizer. A set of SWIPT antenna/rectenna based on frequency splitting are reported in [6], [7], and [8]. In general, in an SWIPT application scenario, a WIT transmitter is positioned far from IoT nodes, causing multipath fading effects, and a separate WPT transmitter is installed near the IoT nodes for WPT. However, the immediately discussed designs employ a single linear polarization for WIT and WPT, which limits the communication range and leads to a high bit error rate and polarization-sensitive WPT operation.