A Pattern Diversity Antenna for Ambient RF Energy Harvesting in Multipath Environments

Abstract

A pattern diversity antenna configuration is proposed for ambient RF energy harvesting in rich multipath environments. The proposed idea is to combine the radiation patterns of three co-centric dipoles with 60° inter-element angle to cover the entire angular space and increase the harvested energy compared to a single dipole. A realistic design is presented consisting of three offset-fed full-wavelength dipoles printed on a low-cost FR4 substrate. By wounding the dipole arms, the antennas are miniaturized, resulting in an overall small size of the receiver which fits in a circle with a 0.3λ0 diameter at 900 MHz. The performance of the proposed antenna is analyzed by a statistical Monte Carlo approach. It is shown that the proposed antenna, despite having a much smaller form factor compared to a spatial diversity configuration with three dipoles half a wavelength apart, provides the same energy harvesting enhancement.