Microstrip Patch Rectenna With High Output Voltage

A prototype dual-polarization microstrip patch rectenna dimensioned for an operating frequency of 8.51 GHz has been built to demonstrate a design concept for obtaining maximum output voltage from a rectenna of a given size. This rectenna contains nine square microstrip patch antenna elements in a square array. The antenna can utilize incident radiation with polarization components parallel to either or both sides of the square because the circuitry under each patch includes two independent rectifiers — one for each polarization component. The dc output terminals of the two rectifiers under each patch are connected in series, and the series rectifier pairs of all patches are connected in series. Consequently, the maximum output voltage (obtainable in the special case of circularly polarized incident radiation) can be 18 times that generated by a single-rectifier, single-polarization patch element.