Comparison between broadband equiangular and archimedean spiral rectennas for energy harvesting

This paper presents a frequency-independent array of rectennas for harvesting low power density RF radiations and converting them to DC power. Two types of spiral antennas; Equiangular spiral and Archimedean spiral are compared to each other in term of the return loss, the efficiency and the axial ratio. The optimized and fabricated antenna is rectified using a Schottky diode. A four-element circular polarized Archimedean spiral rectenna array is designed and fabricated to operate over a frequency range of 0.9-4 GHz. The measured results show that a voltage of 0.8-2 volts can be obtained.