Optimal antenna design for wireless energy harvesting system in ISM band

Abstract

In this paper, three different techniques — Coplanar Waveguide (CPW), Via-less Electromagnetic Band Gap (EBG), and Defected Ground Structure (DGS) — are incorporated to enhance the performance of the designed microstrip patch antenna (MPA). The impact of each technique on the antenna is analyzed. The radiation characteristics of the main, CPW, EBG, and DGS MPAs have been presented and compared. The results indicate that the main antenna design achieved a return loss ($S_{11}$) of −28.3 dB, a gain of 6.31 dBi, a directivity of 7.03 dBi, a bandwidth (BW) of 0.17 GHz, a VSWR of 1.08, and an efficiency ($\eta$) of 84$\text{\%}$ at the 5.8 GHz ISM (Industrial, Scientific, and Medical) Band. While the CPW technique demonstrated an $S_{11}$ of −41.3 dB, a VSWR of 1.01, a BW of 2.18 GHz, a gain of 4.05 dBi, a directivity of 4.45 dBi, and an ($\eta$) of 91$\text{\%}$. Furthermore, the EBG technique resulted in an ($S_{11}$) of −34.16 dB, a gain of 7.24 dBi, a directivity of 7.84 dBi, a BW of 1.43 GHz, a VSWR of 1.05, and an $\eta$ of 87$\text{\%}$. The DGS technique provided an ($S_{11}$) of −34.73 dB, a gain of 6.61 dBi, a directivity of 7.59 dBi, a bandwidth of 1.07 GHz, a VSWR of 1.03, and an ($\eta$) of 80$\text{\%}$. Notably, the simulation and measurement values are in close agreement with impedance matching of $\sim 50\Omega$ and the surface current distribution is quite homogeneous. The substrate’s material is Rogers 04350B with ${\varepsilon }_r=3.66$, the thickness of 1.6 mm, and a loss tangent of 0.0037. The overall size of the proposed design is $50\times 50\times 1.6{\text{mm}}^3$. The proposed structures have an electrical size of $0.967{\lambda }_o\times 0.967{\lambda }_o\times 0.03{\lambda }_o$ at 5.8 GHz, where ${\lambda }_o=27\text{mm}$. This parametric optimization, combined with the novel integration of techniques, contributes a significant advancement in energy harvesting capabilities, making it the most suitable for wireless energy harvesting systems and biomedical applications.