Wireless Power Transfer Test Bed for Rectenna Characterization

A rectifying antenna commonly referred to as a rectenna converts the AC current induced by incident electromagnetic (EM) waves into DC current. Rectennas are increasing in utilization primarily because of their application to wireless power transmission. To understand and characterize the performance of a rectenna, we illuminate it in the far field using EM waves at radio frequencies (RF) and measure its output with an instrument capable of measuring the rectified voltage. The far field of an antenna is generally understood to start at a distance of 2D2/lambda where D is the largest physical linear dimension of the antenna and lambda is the wavelength of the incident EM. This region allows for a flat magnitude and phase across the antenna aperture. These requirements made the modification of our small anechoic chamber ideal as an RF source, positioning equipment, and acquisition software were already in place. However, the challenge was to measure the resultant DC voltage at each aspect angle as a function of the power density incident on the rectenna under test (RUT).