Coplanar Waveguide Fed Ultra-Wide-Band Monopole Antenna for Radio Frequency Energy Harvesting Applications

The RFEH based on wireless charging is a promising technology for powering low-energy Internet-of-Things (IoT) devices; however, its efficiency is still limited by antenna design and impedance matching. In this work, a printed antenna suitable for RFEH is developed with a CPW feed. The antenna is composed of a semicircular fractal curve, similar to a fig leaf tree radiating patch, with rectangular notches to be fabricated on an FR4 low-cost substrate. It has an operational bandwidth of 700 MHz to 3 GHz, covering key communication bands, including GSM, WLAN, ISM, and Wi-Fi applications. Numerical simulations were performed using computational electromagnetic modeling software. The experimental work demonstrated the suitability of this antenna for stable omnidirectional radiation patterns and successful RF-to-DC conversion efficiencies at the five target frequencies, including 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, and 2400 MHz. The antenna shows potential for powering low-energy IoT devices in ambient RF conditions. The proposed work aims to compare the measured and simulated results. Lastly, the numerical and experimental results are compared and show remarkable agreement.