Design and Implementation of Multi-Band Fractal Slot Antennas for Energy Harvesting Applications

Abstract

This paper introduces a design and optimization procedure of multiband fractal slot antennas for RF energy harvesting applications. The antennas were simulated using CST Studio Suite. A parametric study is conducted to determine the critical structural parameters that influence the antenna performance. The parametric study included varying the size ratio of the structure, the shape of the ground plane and the length of the feeding inset. Simulation results showed that the proposed antennas in this work exhibit multiband performance and they offer the possibility of controlling the resonant frequency at any specific frequency band. The optimized antenna has seven resonant frequencies at 1.8 GHz, 2.4 GHz, 3.45 GHz, 3.6 GHz, 4 GHz, 4.6 GHz and 5.3 GHz covering several ambient communication networks (GSM, UMTS and 5G), Bluetooth and WLAN systems. Simulation results shows that Antenna 1 has achieved a gain of more than 4.5 dBi at all the resonant frequencies with a radiation efficiency ranged between 87%-95%; whereas Antenna 2 has achieved more than 3 dBi gain at lower frequencies while reaching around 7 dBi at higher frequencies with a radiation efficiency ranged between 80%-97%. Finally, two fractal slot antennas were fabricated and tested in the lab to validate the simulation results and to proof the concept of the feasibility of this type of antennas for this application. Experimental results showed a good agreement with simulations.