Semi-Annular-Ring slots loading for broadband circularly polarized DR-Rectenna for RF energy harvesting in smart city environment

This article describes a circularly polarized (CP) broadband rectenna enabling sensing nodes connected in the smart cities to harvest radio frequency (RF) energy from the surrounding atmosphere. The proposed antenna efficiently operates at the 5.8 GHz Wi-Fi band (5.725–5.875 GHz) and the Wi-Fi 6E band (5.925–7.125). The antenna is a semi-cylindrical dielectric resonator antenna (S-CDRA) energized by a microstrip feed. Semi-annular slots are introduced around a Bow-tie slot from the ground plane side, enhancing the bandwidth, gain, and CP characteristics. The antenna provides an impedance bandwidth (BW) of 2.89 GHz (5.45–8.34 GHz) and offers CP characteristics with an axial ratio (AR) bandwidth of 680 MHz (5.67–6.35 GHz). The antenna maintains a minimum gain of 4.8 dBic. A series-pair configuration is proposed for an extended operating range and better conversion efficiency. The maximum simulated and measured conversion efficiencies are 66.6% and 65.2% at 11 dBm input power, respectively.