Broadband rectenna for ambient RF energy harvesting applications

In this paper, a broadband rectenna, for ambient RF energy harvesting applications, is presented. It is composed of a broadband spiral antenna with its balun, optimized to cover the principal frequency bands where there is RF energy to harvest (GSM900, GSM1800, UMTS2100 and WIFI). This antenna will be associated, in a first step, with a dual-band rectifier (GSM900-GSM1800) to do a complete rectenna. Source-pull simulations have been used to determine the optimal diode impedance giving the maximum conversion efficiency, in frequency bands of interest, for low input RF power levels. A broadband matching network has then been synthesized to ensure optimal operation of the rectifier in the GSM900 and GSM1800 bands.