Design of a hexagonal slot rectenna for RF energy harvesting in Wi‐Fi / WLAN applications

Abstract

This work proposes a single port hexagonal slotted rectenna operating at 2.45 GHz Wi-Fi bands, using a hexagonally slotted shape of microstrip radiator surface followed by a voltage rectifier circuit using Schottky diode. A symmetrically extended ground plane and rectangular slots help in obtaining the desired resonance characteristics with improved antenna bandwidth. Three different antenna designs have been compared and analyzed. Best gain and wide most bandwidth is seen in the newly designed rectangular and hexagonal slotted design having symmetrically extended ground plane. A RF capacitor and inductor based matching network has been designed to maximize the wireless power transmission at 2.45 GHz. This also helps to enhance the rectifier efficiency for various values of load resistance and input power. Furthermore, for maintaining the small size and ensuring least amount of energy loss, the rectifier's ground has been directly connected to the antenna's ground plane. The proposed design has been simulated in HFSS and ADS software, prototyped, and measured. It has been seen in the results that, the proposed radio frequency (RF) power receiving antenna is performing very well at 2.45 GHz with a wide bandwidth ranging from 1.25 to 2.63 GHz. The proposed rectenna is having a maximum efficiency of 62.4% at 2.45 GHz with an input power of 0 dBm. Furthermore, with variations in the load resistance across a wide range of values from 4 to 12 kΩ $$ \mathrm{k}\Omega $$ under a wide range of low input power, the rectenna maintains an efficient power conversion, which is found to be an important parameter when the ambient RF signal input to the antenna is weak. As a result, the rectenna may be adaptable to a variety of low-power electronic circuits by harvesting RF energy at 2.45 GHz Wi-Fi Band. Furthermore, the proposed antenna can also be used for wireless medical telemetry, satellite phone and Wi-Fi applications used for the frequency band 1.45 GHz as well.