Design of a Broadband Circularly Polarized Rectenna for Applications of Microwave Power Transmission

Abstract

This dissertation presents a broadband circularly polarized rectifying antenna (rectenna) for microwave power transmission at 4 2-7 6 GHz comprising a broadband circularly polarized (CP) antenna and a rectifier circuit This antenna finds its application for C band (4 to 8 GHz) that can receive more microwave power at different frequency Moreover the designed rectenna can be further researched to combine with microwave switch circuit for data communications The CP antenna consists of an improved Schiffman phase shifter with easy implementation and use to provide a wideband phase difference of 90° It also includes a pair of orthogonally positioned linearly polarized (LP) slot antennas with equal radiation strength that are used to accomplish a circular polarization by combining the horizontally and vertically polarized waves with a Wilkinson power divider The proposed rectenna has an improved design and implementation using a broadband CP antenna that features a size reduction good axial-ratio bandwidth and good return loss bandwidth In addition the rectifier circuit is composed of a microwave Si Schottky detector diode (HSMS-2862) a low-pass filter a load resistor and a bypass capacitor The output dc voltage of 1 98 V over a 680 Ω load resistance and the maximum microwave-to-dc conversion efficiency of 81 6 % were measured when a 34-dBm microwave power was transmitted at 5 6 GHz over a distance of 50 cm which was referred as the far field The designed rectenna was printed on a double-sided FR4 substrate of thickness 1 6 mm with dielectric constant 4 4 and the simulation tools used in this study include Microwave office Matlab and Ansys HFSS

Date of Award	2015 Apr 27
Original language	English
Supervisor	Chien-Hsing Lee (Supervisor)