Wireless power transmission (wpt) application at 2.4 ghz in common network
Creators: name: Yeoh, Wai
Publisher: name: RMIT University
Year: 2024

description: Wireless Power Transmission (WPT) technology by electromagnetic propagation coupling has been under active research and development due to the emergence of wireless technology. This dissertation presents an analytical and experimental study to design rectenna prototypes and to investigate the feasibility of a WPT system which harvests energy at the 2.4GHz ISM band in compliance with the FCC’s maximum emission regulation of 36 dBm Equivalent Isotropic Radiated Power (EIRP).<br><br> This research work includes the design and development of rectenna, which consists of antenna and rectifier. These components are specifically designed to occupy the smallest form factor possible for consumer device integration. The proposed miniaturised rectifier is the Villard’s Voltage Doubler (VVD), which has been optimised to provide over 70% DC conversion efficiency at 2.4GHz ISM band within preset input power range. <br><br>The major innovation is in the area of the antenna miniaturisation. A Miniaturised Half Bowtie Printed Dipole Antenna (MHB PDA) with integrated balun is designed. It possesses omnidirectional-like radiation patterns and 47% bandwidth with only 0.36λ size, centralised at 2.97GHz. It covers ISM band at 2.4GHz and suitable for multiple wireless communication standards. To reduce the capacitive ground plane effect caused by the consumer device, Half Bowtie Yagi-Uda (HBYU) antenna, HBYU collinear array and the Decoupled Dual Dipole (DDD) antenna are designed and they operate at 2.4GHz band. The HBYU (6.7dBi) and HBYU collinear array (8.8dBi) are printed antennas which have 1cm spacing from a conducting surface. The DDD is a pair of antennas (4.5dBi) with a compact decoupling structure in between, which enables integration of two identical antennas with narrow spacing (3mm) in between. Furthermore, the spacing is only 5 mm. <br><br>The first rectenna is MHB Printed Dipole Rectenna (PDR), which is designed by integrating the rectifier into the MHB PDA. The minimum range for it to produce 1VDC from the transmitter is 2.3m. Next, the high gain HBYU Collinear Rectenna Array (HBYU CRA) is designed to produce more than 1VDC within 4m range. It can fully charge the NiMH batteries (4.8V, 900mAh) up to 5.3V at 23cm away from the transmitter. For a Li-Po cell pack (3.7V, 1100mAh), it is able to charge it from 3.46 V to 3.62V in 330 minutes. At 10cm, it is capable to prolong Nokia’s Li-Po cell pack cycle life by 31 minutes during video playback. To achieve smaller dimension, the DDD Rectenna (D3R) is designed by integrating the VVD at the centre of the DDD. Apart from that, the output of D3R can be wired into parallel or series configuration depending on the applications. Lastly, the D3R optimal array distribution is introduced to improve the DC gain by at least 56%. <br><br>This research study has demonstrated the possibility of implementing the WPT technology in battery powered applications. The feasibility of the proposed system is highly application-specific in terms of power requirement and physical dimension. The wireless power transmission technology using WLAN band is possible to be a successful energy harvesting technology in future for low-power applications.<br>