Circular Polarized Elliptical Microstrip Antenna with Wide Beamwidth for ISM Band RF Energy Harvesting

Abstract

A coaxial-fed elliptical microstrip antenna having circular polarization is presented for harvesting RF energy in the ISM band. A square-shaped slot is embedded in the elliptical microstrip antenna which causes current perturbation. The position and dimension of the square slot are optimized to generate the two orthogonal degenerate modes required for circular polarization. V-shaped slits that are placed diagonally along the boundary affect the resonant frequency. The proposed design has a simulated 10-dB impedance bandwidth equal to 100 MHz (2.43 GHz-2.53 GHz) whereas 3-dB AR bandwidth is 20 MHz (2.45-2.47 GHz). The simulated gain of proposed antenna is around 3.35 dB. The design generates a wide AR beam width of 160 degrees in E-plane and 200 degrees in H-plane. The overall antenna dimensions are $50\ \mathbf{mm}\times 50\mathbf{mm}\times 1.6\ \mathbf{mm}\ (0.41\ \boldsymbol{\lambda}_{0} \times 0.41\boldsymbol{\lambda}_{0}\times 0.013\ \boldsymbol{\lambda}_{0})$. The antenna is suitable for use in ISM band for RF energy harvesting from nearby WiFi, Bluetooth devices.