Study on Millimeter-Wave SIW Rectenna and Arrays With High Conversion Efficiency

A novel aperture-coupled patch rectenna backed by a substrate integrated waveguide (SIW) cavity operated at 35 GHz for millimeter-wave power transmission (MMPT) with high conversion efficiency is presented in this article. A four-element SIW patch array with a harmonic suppression function based on the barbell-type defect ground structure (DGS) is proposed as the receiving antenna; thus, the low-pass filter in the rectifying circuit can be omitted. The Schottky diode is parallel-mounted in the rectifying circuit, which has a measured rectifying efficiency of 61.2% with a $500~\Omega $ load when the received power is 100 mW. The maximum conversion efficiency of the rectenna element is 60.9% when the received power is 79.4 mW. Additionally, 4–8-and 16-element rectenna arrays are also investigated to obtain high direct current power. When the power density is 9.2 mW/cm2, the conversion efficiencies of the rectenna element, $2\times2$ array, $2\times4$ array and $2\times8$ array are 50.5%, 44.1%, 41.9%, 38.9%, respectively. The measured conversion efficiency of the $2\times8$ rectenna array at 35 GHz is 49.2% when the input power is 1259 mW. The low profile and easy integration of the studied rectenna will make it easy to expand its use to large-scale arrays for high-power MMPT applications.