Design of Dual-Band Circular Microstrip Patch Antenna with Slot for Energy Harvesting Applications

In this paper, a small-sized dual-band circular microstrip patch antenna along with an integrated slot is introduced for RF energy harvesting purposes. The introduced antenna includes a circular patch and a slot, which allows the antenna to work in two operating bands in addition to being very compact. The presence of a slot makes a larger path for the effective current, which leads to the miniaturization of the antenna and excitation of the lowest operating band. After designing the size of the antenna, the circular patch is able to resonate at the highest band of 4.94 GHz. Through optimal design of the slot shape, the lowest resonance frequency of 2.19 GHz is achieved, which allows the antenna to be used in harvesting the ambient RF energy from ISM and WLAN band sources. The antenna has been designed on a cheap FR-4 substrate having a dielectric constant of 4.4. The simulation results show great performance of the antenna in terms of impedance matching with a return loss less than -10 dB in both operating bands, a VSWR close to 1, stable radiation properties, and acceptable gain, which enables it to harvest the RF power efficiently.