RF harvester for DC supply

Abstract

This project focuses on the design of 2GHz rectenna for harvesting RF signal. This 2GHz signal is from a 3G signal and ISM band that is easy to be found in town areas. The rectenna comprises an array of rectangular patch of microstrip antenna, power combiner and voltage multiplier. Patch antenna was designed using a CST Microwave Studio 2012. The following parameters: return loss, bandwidth, radiation pattern, voltage standing wave ratio (VSWR), input impedance and antenna polarization were obtained from simulation. The power combiner circuit was designed using a Wilkinson power splitter. A power combiner for six stages and 64 inputs was proposed, designed and evaluated. The performance was done by simulation using ADS 2009 software. Two multipliers, three and six stages voltage multiplier were designed and evaluated using the same software. After designing and simulating, the following results were obtained. The designed antenna was simulated and it obtained 44.4dB of return loss with 400MHz of bandwidth, 1.01:1 of VSWR, 50Ω input impedance and 6.202dBi of directivity for the radiation pattern. A full analytical study of power combiner was done and simulation results are presented. The design of the power combiner obtained a 9dB output gain for three stages power combiner. A six-stage voltage multiplier has been simulated and it had a 3.901V of output voltage for the input voltage of 1V. The power produced by the harvester is 20mA. However, there were some harmonics shown by the ripples on the graph. The ripples can be reduced by adding the capacitor of a higher value. In conclusion, the proposed designs have been successfully designed and the simulated results have been obtained within the specifications.