What is a rectenna and how does it work?

A rectenna (short for rectifying antenna) is a device that receives microwave energy and converts it directly into direct current (DC) electricity. It consists of two functional parts: a receiving antenna element (typically a dipole or microstrip patch) that captures the microwave radiation, and a rectifying circuit using a diode that converts the alternating electromagnetic signal into DC current. Individual rectenna elements are small, typically a few centimeters across at microwave frequencies used for SBSP. A full SBSP receiving station would consist of an array containing many millions of rectenna elements arranged across a large ground area, collectively capturing the transmitted beam and delivering aggregated DC power to the site's electrical output. The concept was first demonstrated by William Brown at Raytheon in 1964, who achieved DC output from a microwave beam using a rectenna. Individual element conversion efficiency can exceed 80% under optimal conditions. Total system efficiency from transmitted beam to grid-ready power is lower due to aperture losses, propagation losses, and power conditioning stages.