Compact circularly polarized beam-switching wireless power transfer system for ambient energy harvesting applications

Abstract

In this work, we propose a circularly polarized (CP) beam-switching wireless power transfer system for ambient energy harvesting applications operating at 2.4 GHz. Beam-switching is achieved using a low profile, electrically small CP antenna array with four elements and a novel miniaturized 4×4 butler matrix. The CP antenna is designed with an e-shaped slot and four antennas. The CP antenna measures 0.32λ 0 ×0.32λ 0 ×0.006λ 0 at 2.4 GHz. The antenna has a gain of 3 dBic and an axial ratio less than 3-dB at 2.4 GHz. A linear antenna array consisting of four elements is designed with the CP antenna element with an inter-element distance of 0.29λ 0 . A 4×4 butler matrix with miniaturized couplers and crossovers are used to feed the four antenna array elements. Based on the input port of excitation, the main beam of the antenna array is demonstrated to be switched to four directions: −5 , 65 , −55 , and 20 . A CP rectenna is used to demonstrate the wireless power transfer capability of the combination of the butler matrix and the CPantenna array. The rectenna consists of a Teo-shaped CP antenna and a rectifier. The open circuit voltage at the output of the rectenna is found to peak value of 30 mV at −3 , 61 , −53 , and 17 . Thus a complete system for CP wireless power transfer including the power transmission system as well as the RF energy harvesting sensor is designed and experimentally verified. K E Y W O R D Sbutler matrix, circular polarized rectenna, RF energy harvesting system, wireless power transfer

A Novel Design of Broadband Circularly Polarized Rectenna With Enhanced Gain for Energy Harvesting

“…These include a symmetric-aperture achieving broadband circular polarization antenna with coplanar waveguide (CPW) feed [2], an octagonal-shaped aperture antenna backed by artificial magnetic conductor (AMC) layers for wireless applications [3], and for enhanced wideband capabilities, AMC surfaces like square-loop is used along with hexagonal-shaped aperture [4]. A compact circularly polarized beam-switching system is designed for efficient wireless power transfer at 2.4 GHz [5]. Achieving optimal power transfer from antenna to rectifier requires careful impedance matching techniques for single-band [6][7][8][9][10][11][12][13][14][15][16][17][18][19], broadband [20][21][22][23][24][25], dual-band [28][29][30], and multiband [31][32][33][34] rectifiers.…”

A High-Performance Circularly Polarized and Harmonic Rejection Rectenna for Electromagnetic Energy Harvesting

“…However, this comes at the cost of increasing the size of the receiving antenna, which is dependent on the number of elements used. As a result, there is an increasing amount of research being dedicated to the development of compact and highly efficient antenna elements, which can enable the realization of high-performance antenna arrays in a small form factor [ 14 , 20 , 21 , 22 ]. Therefore, an antenna structure that combines harmonic rejection, higher directivity, and efficiency could be a good candidate for low-cost and compact energy harvesting.…”

Compactmulti‐frequencysystem design forSWIPTapplications

“…In this context, there has been a growing interest of researchers in the development of the WPT systems. In particular, there is an increasing interest in near-field WPTs as they have a broad application area, such as implantable medical devices, 3 consumer electronics, 4 low-power sensors, 5,6 radio-frequency identification, 7,8 wireless body area network, 9 and so forth. In general, there are three distinct techniques to achieve near-field WPT, namely, capacitive, 10 inductive, 11 and magnetic resonance.…”